Can you change your Linux distro

Theoretically yes, practically no.
+1 for openSUSE btw.

The real question is all the stuff beyond just having the distro installed. The packages, the services, the configs, the application data.
If you leave all that stuff the way it was installed via the old package manager, it may have some bad assumptions baked in and may be incompatible with packages you install with the new package manager.
And if you clear all of it out and reinstall it, have you really gained anything vs. just doing a clean install?
There’s a reason you have a home dir. Just copy that forward along with whatever other config files you might’ve customized.
Btw, if the ability to make drastic changes while still maintaining continuity is an important feature for you, maybe check out NixOS.
- There’s a reason you have a home dir. Just copy that forward along with whatever other config files you might’ve customized.
  This is probably the reason why most distros will have the home directory on a separate partition. To easily allow you to keep your most important data when reinstalling or switching to a new distro.

- Personally I don't use a separate /home partition. Software versions can differ significantly between distros and this has plenty of potential to effectively fuck up your system anyhow*.
  I use a separate data partition instead, and hook it into my home with symlinks. Pictures, Documents, Videos etc. - these are usually those that take the most disk space anyhow, by a large margin.
  
  I just use restic to backup my home (to a local disk as well as weekly remote syncs). Then whenever I switch distros I just restore the files I want.

THANK YOU ALL for your replies. I'll do a clean install and made a backup of my files (was not difficult bc most stuff I have in the cloud). I'm moving indeed from Mint to OpenSuse Tumbleweed. I don't know exactely why, but it seems to me an interesting thing to do. Still figuring out what distro fits me best.
- A useful setup for the future is to keep home as a separate partition. Then you should be able to reinstall a different distro on the root partition and have all the data carried over. There is some bleed over in that all your dotfiles will carry over, but usually that doesn't break anything and is usually a plus (e.g. all your firefox addons and preferences will immediately be applied in the new install)
  
  This.. This is a just good practice. That way you can go buck wild on your home partition. Additionally, you'll never accidentally have to deal with booting into your system with 0 free space on root. It's an easy fix but why have to deal with it
- Excellent choice. I did the same last year. I'm still on Tumbleweed.
- Welcome to distro hopping! If at some point in the future you want to try another out but don't want to start from scratch, there are ways to demo them to get a feel and see if it's something you'd like to take the effort to wipe and install.

No, the package systems, management tools, and configs for Debian (what Mint uses) and OpenSUSE are different. Technically, if you had tons of time and a solid understanding of Linux inside and out, you might be able to pull it off, but it's not worth the hassle at all.
- I’ve read some stories of someone transmuting Ubuntu into Debian or something like that. It requires lots of knowledge of both systems, plenty of time, and infinite patience. The two distributions should be somewhat closely related in order to make this gargantuan project even remotely feasible. If you’re jumping from Arch to Gentoo, you might as well just do LFS while you’re at it.
  
  I believe you can install the Arch package manager on gentoo
- Technically, if you had tons of time and a solid understanding of Linux inside and out, you might be able to pull it off, but it’s not worth the hassle at all.
  This is what I thought. Preferably “from the outside” i.e. while the system isn’t running. But all you “saved” in the end is the filesystem the original OS was installed on, and possibly personal data (which probably is the reason OP is even asking).

For all intents and purposes different Linux distros are different operating systems, built with some number of overlapping components (including the Linux kernel after which they're named) so unfortunately no :/
Best of luck to you in whatever changes you decide you wanna pursue!

@Wimster Yes, but it takes much longer and requires a very good knowledge of your future distro.
You need to manually unpack packages of your future distro ijnto soem folder to create a chroot environment that is able to run the package manager of your future distro. Chroot into that and install the software for a minimal bootable environment. Move your new distro environment to the root dir of your partition, remove the old stuff and configure your boot manager. Then you can boot into your new minimal distro and install whatever you want.
Debian has some programs to help you with the first steps, like debootstrap (for .deb based distros) and rinse (for .rpm based distros, like OpenSUse).

There's nothing stoping you from gutting your distro and installing new kernel, libc, package manager, toolchain, and all the other components. The GUI should be trivial as people have change back and forth among different ones (within the same distro) anyway, assuming your package manager.
Of course, this begs the question: why the fuck would you do that instead of just installing a new one fresh?

+1 for NixOS. My desire to have a reproduceable system got me to this and does just the job for me.

Somebody the other day asked what the point of the immutable desktops are. Well, ostree can do this. Granted, you have to stay within the ostree ecosystem. However, you can rebase from one ostree distro to another.

That depends on a couple of things:
If you have a separate partition for /home (your personal data) it is pretty easy since you can reinstall the system, leave /home untouched during installation and just configure it to be used as /home in your new setup.
This does not work if you either do not have a separate /home partition or you encrypt your system via LUKS.
It technically still is possible in the aforementioned cases but involves expert knowledge and probably a lot of manual steps which I'd say for you and me it probably is impractical.
- It's totally unproblematic to use an existing encrypted partition even without a separate home partition. You just unlock your drive and delete everything except for home. Never encountered a single installer that couldn't handle it.
  
  Might be wise to not accept the offer of the installer to partition the device in this case. That's self–evident to anyone who lived through losing data, not so for beginners.

What made you want to make the switch? I’m currently on Mint
- I'm still in the fase of exploration. When using Windows, you just have 1 choice. I just want to discover what suits me best. So nothing against Linux Mint. It's great, but maybe OpenSuse is better for me? I don't know.
  
  Just boot to a USB for a low-risk test.
  
  just in case you dont know, Distrosea lets you try various distros online which is handy just for getting a quick idea what the UI is like
  for trying out different distros using the live USB method, Ventoy is a good option since it lets you have multiple ISO files on your USB drive at once, instead of having to reformat your USB each time

From very stable and boring distro to rolling release distro is good experiment. Rivals to your future choice are Manjaro, Arch, maybe Fedora. Are you certain about the SuSE? 😉

As others have said, not with Linux Mint.
However if you were running an atomic distro such as Aurora, Bazzite, Project Bluefin, or Fedora Silverblue you can "rebase" from one to another.
With an atomic distro all the system files are immutable, you can read them but only the OS can change them. As there's a clear distinction from user files (anything in /var or /home) the OS can simply replace all the system components with a new distro and re-mount your files.