There is! Fair warning that it's a little bit clunky. (which is to say, you may have to manually push buttons to commit/push/pull) I'm not the author, just a happy user.

https://github.com/denolehov/obsidian-git

I don't use Android anymore but when I did I found the GitJournal app worked well to sync with git, then you could open the files with Obsidian.

That predates plugins being native on mobile apps however, so the built in Obsidian Git plugin might be better now.

There is also another one: using the self-hosted LiveSync plugin.[0] This uses CouchDB.

[0]: https://github.com/vrtmrz/obsidian-livesync

Got it synced over laptop, android phone and tablet with syncthing. Whith my home server as 'base' which also backup the vault itself

I've been using syncthing to do this without any issue.

I've found myself running into sync-conflicts while editing my Obsidian Vault in a syncthing folder in the past. Did syncthing work flawlessly OOB in your experience?

Yes I second this! Syncthing works really well for keeping Obsidian vaults sync'd across multiple computers