Is there a viable Photos alternative? I was thinking of setting up a NAS on my RPi but it would need to be for other family members too.

Cs-137 and other fission and activation products can be largely removed by treatment. H-3 is a bit trickier since it literally is part of the water. Luckily it’s a fairly weak beta emitter with a relatively short half life so causes very, very little long term harm.