> I can't imagine trying to maintain an app on there that would actually be the first class storage/sync/presentation layer for my family.

Immich exists. It really is missing only some editing functionality and some nice-to-have features from GPhotos like automatic panoramas. Other than that, it's superior to Google.

Immich feels too heavy for my needs, so I wrote a single executable server that turns my photo directories into a photo gallery (https://github.com/yhling/go-web-image-gallery)

Photo ingestion is via regular samba uploads from my phone.