>But man is it remarkable that an open source project can rival something from Google in terms of quality and experience.

I'd argue Google is always way worse than the open source alternative in both quality and ux. Their products are terrible. From Gmail to Youtube, the product itself comes second (or Nth), while in open source the product is always first.

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).