I know this can be an unpopular opinion but you’ll be fine. Even with less if needed. Of course there are ideal configurations but I can tell you from my own experience that it is more important to have a place to store your data (and maybe even a second one as a backup) than to have no place because you are waiting for the “perfect configuration”. My humble opinion: Look at old systems, other peoples systems in the forums, and your budget. Get what you can afford now - maybe even what hurts a little but is still possible - and build your system(s). If you check compatibilities and such, you will be fine.
Personally, I have a mix of different systems. From very old ones that are nowhere near the recommended specs (but working fine) to newer ones that are kinda in the sweet spot. And yes, in a perfect world you have a 3-2-1 backup solution with one being off-site and in climate controlled environments, and with spares, and UPS, and redundant backup power supplies, and backup power lines, and backup Internet, and service agreements… But having your photos stored on a NAS and not only your phone/computer is already many times better than not. We enthusiasts tend to forget that.
Edit: Look at this thread and you’ll see examples of people running old systems that are just fine. And you can always use a MiniPC or old stuff for Jellyfin if your NAS is only good as a NAS.