Should I go with a prebuilt or custom built NAS to get into self hosting?

Hey all, I've been doing a bunch of research on selfhosting the last few weeks as I'd love to lean on more open source projects for my daily productivity & entertainment. My main goal is to backup all my personal documents, photos, and videos (around 1tb so far over ~5 years, so not too demanding) and host a few services to access files on local storage (Immich, Jellyfin) and personal (paperless-ngx, homeassistant, morss). Although I'm not afraid to mess around learning Docker, I'd like to prioritize low maintenance in balance with relatively low long-term cost so that I don't run into an issue that takes more than a day to restore access to my files/backups. I'd rather save that time for the fun stuff, like endlessly configuring HA automations.

All that said, I figure a decent solution would be to run a local NAS in RAID 6 with a cold storage HDD to swap whenever I transfer a bunch of files from my camera for local backup, and a remote backup at either my parents' home or maybe eventually on another friend's NAS. The main thing I'm wondering right now is if a prebuilt NAS (Synology, Asustor, etc.) is worth it in comparison to a custom built system for simple maintenance, reliable and low-bandwidth remote backup and recovery, and solid file sharing options for friends and family? I've heard SFTPGo is a great project for file transfers if going custom built, so I'm not completely worried about the last point, but it'd still be a nice bonus to not have to worry about another service.

My greatest fear is having to explain to my parents what a terminal is, so I'd like something reliable with a good price which I can hopefully maintain without crossing that bridge. I know most prebuilt NAS systems aren't as cost effective or flexible for hosting a bunch of services also, so if I did go with a prebuilt, I would probably pick up a micro PC like a NUC or an old Dell Optiplex to network with the NAS for Immich, and maybe use some internal storage to keep some movies to stream with Jellyfin (unless there's a limitation I'm not considering). Any advice?