Since you're comfortable hosting your own servers, you could try Piwigo. I used it ages ago (it's been at least a decade by now) for a few small galleries on a personal site, and it looks like it's matured a bit since then. They appear to have mobile apps now for uploading and managing your galleries.
https://github.com/Piwigo/Piwigo
https://piwigo.org/guides/install/manual
Beware that it's PHP on MySQL. So, definitely follow all your usual security precautions.