Just a shameless suggestion: if anyone is concerned about the security implications of using the Obsidian Sync paid addon, I’ve been having good results with Syncthing instead. It supports peer-to-peer sync and is FOSS.
I guess I fit solidly inside the 5GB free tier and probably will for quite a while.
I would use Dropbox but the app feels quite heavy and it wasn’t very easy to set up on iPhone.