Brave
I recently switched to Brave after getting sick of trying to configure media playback to work in a reasonable way on Firefox. I don’t like everything about Brave, but with a bit of tweaking, it makes for a good, relatively Google-free, browser.
There’s little to no documentation on how to self-host the Brave Sync Server, which allows to synchronize bookmarks, tabs, settings and much more between devices.
The sync server, like the browser itself, is open source and can be found here: https://github.