Yeah I’m not a big fan of NAS’s. I agree they’re a bit of a ripoff, you’re paying for convenience. The only reason to go with a NAS imo is if you’re unable and unwilling to learn to use linux. Raspi4 are pretty cheap, 4gb model is like $55 iirc. If you’re paying more you’re probably getting ripped off. It’s definitely going to be lower power usage than a NUC or mini PC. But maybe you can find a cheap used one.
But since you’re only hosting photos, pretty much anything should work.