Your options will depend on many things…

• How much storage is needed?
• Is RAID important to you?
• Is power usage a concern?
• Noise level?

I don’t know how demanding photoprism is, but you could probably do fine with a refurbished i5/i7 Dell Optiplex or similar, with one or more SSDs added to it. If money is really tight and storage needs are high, you could go with mechanical drives instead.

The problem with enterprise servers is that are generally very loud and use a lot of power…not unlike adding a second refrigerator to your environment. In my opinion, they’re not worth it unless you have a specific use case (training for a career, etc.).

I’ve been very happy with both Silverblue and Kinoite. I’ve installed it to all of my workstations now and can’t imagine ever going back to a traditional distro.

Your comments suggest that you’re already aware of distros like Silverblue so, if I may ask, how are these different than what you’re looking for? Silverblue comes with several flatpaks installed, but you can easily remove these and you’ll be left with a pretty barebones ostree image.