Been running raid1 on USB for over a decade. Avoid chaeap USB stuff, get foot brand USB boxes and preferably a JBOD multi-disk enclosure, since they tend to be the best quality.
Never had a disconnect.
Beware to properly label your driver tough, as Linux software raid (I use that) tend to hiccup on boot if the kernel reassign USB devices after a reboot.
Many people suggest immich or photoptism, but those are not the correct tools for this use case. Piwigo us great, but in my esperience slow and clunky. Lychee is great tough and probably the correct answer to op.
Check this wiki, specially the torrebt and Usenet pages… Then you can wither follow the practical installation pages or ignore and find some docker only guides.
Be careful not to burn the Linux bridge by being not able to support the transition now… :)
Edit: what I mean is, if you are responsible for this transition, now study study study… Be very careful and test each setup on a “test” machine before going to deploy for others…