The android app developed by the syncthing dev is deprecated, the fork is still fine. While the fork’s dev has no plans to publish to google play, there’s presently no reason to think they will discontinue supporting the fork.

Yeah this.

I don’t keep all my photos in sync though. Only the last few months.

I’m using photoprism to browse photos on my server but I’ve been meaning to look at other options because it’s not that great IMO.