Without technical know-how or experience in general using NAS, Synology is a good first-time option. All apps are ready for immediate use. And don’t forget the majority of computer users don’t even know what a NAS is and they simply want to store files for remote access.
You could ask the question for video gaming. Can a used computer do the job? Yes, but you may not be able to play cutting edge / demanding games if your computer lacks the appropriate hardware. It really depends what kind of things you want to do, for choosing hardware that’s powerful enough.
Jellyfin? You need to consider if you need transcoding. Transcode or not makes quite a difference on the hardware needs.
I feel like I’m doing something illegal by calling my home a lab. Might be thinking too much ;) Jokes aside, I’m not really testing or inventing anything so I genuinely don’t understand where the lab part comes from.