In my experience, most open source photo apps lacked basic features like facial recognition, mobile apps, etc. And where they do exist, the UX isn't the best. Are there ones I'm unaware of?

I say this as someone whose last startup (circa 2012) was an open source photo app (https://github.com/photo/frontend).

I think it's a testament to how far computers have come that identifying the individuals in a photograph is now considered a basic feature.