So that’s admittedly not a good look for canonical, but my read of that is that if you’re getting widely-known software from a developer who’s publishing it to snap themselves, and you’re cautious about your usage, snap is fine.
For example, essentially my only use of snap is to install certbot. If I follow the directions from certbot.eff.org precisely, then I’ll get certbot installed and no issues.
I certainly agree that (a) the system is ripe for abuse and (b) should be self-hostable to support Free software. Both of these could be fixed by canonical opening it up.
Would Plex be an option here? I don’t use it, but I know it has a photo library feature.