Should I just rsync/Syncthing my photos off my phone to NAS and use Adobe Bridge/Finder/anything? :D
https://github.com/awesome-selfhosted/awesome-selfhosted#pho...
Yes. If SyncThing gives you attitude, try PhotoSync and Resilio Sync.
But whatever you do, keep your originals.
Know that GitHub is littered with abandoned gallery projects. I helped maintain one of the most popular open-source galleries more than a decade ago, and it was hard to stay motivated when there were daily encounters with Internet Monsters. I don't blame any dev for walking away from that morass.
I'd tried tons of open source and commercial solutions, and couldn't get one that handled my mess, so I built one: https://photostructure.com/about/introducing-photostructure/
I'm making it available for free during the beta, in exchange for your feedback.
Regardless of whether you go with what I've built, you may want to at least be aware of these features, so you can pick a solution that minimizes your future regret: https://photostructure.com/faq/why-photostructure/
XnView MP: https://www.xnview.com/en/xnviewmp/
I have it set up with my Dropbox folder so the photos in there sync around to different devices.
Not really a cloud replacement, but it works pretty well for what it is.