How do i find remote communities v2.0

While typing the title i found some existing posts, but they don't really answer the question as well as I'd like.

The typical recommendation is to use some external web page that is not actually a lemmy instance.

This means if I'm using lemmy from within an app I have to pop into a web browser, find what I'm after copy anything needed to clipboard and pop back into the app ready to paste / re-format / search.

This sounds really not streamlined.

Other solution is to have a couple of accounts and flip between them and search each home instance for what I'm after.

I'm not sure I'm clear on what I'm asking so i'll give an example...

I'm on lemmy.world, there is a community on lemmy.radio/c/amateur_radio Let's assume i don't know this however.

a) How would i find this while logged into the lemmy.world website? b) How would i find this while logged into the lemmy.world via an app?

If this functionality does not exist that's fine, but all I've heard about federation makes me think it does exist and i haven't found it or don't understand it (hence why i think I'm asking a dumb question).

Is there a foolproof legitimate way to browse or search a list of communities on another instance without going to that instance or using a third party site?