I am gradually moving everything to self hosted, and I want to move away from Google Photos. I currently have Nextcloud and sync seems to mostly work, but the default interface seems a bit lacking.
I have tried a few things a while ago (~6 months), but things seem to change quickly.
At the moment, I quite like Nextcloud Memories. It has a similar interface to Google Photos and seems to have relatively quick photo caching, and integrates well with nextcloud. However it doesn’t have a real app and lacks of offline viewing so haven’t fully transistioned yet.
I like Photostructure as a way to browse my photos. It does logical deduping, and automatic organization of your photos (if you want it to). Like some others mentioned in this thread, it's a very young software, but the developer is very active and transparent about the progress.