Since you're already storing your notes in Git, I think GitJournal [0] might be useful for you. It's an open source mobile first markdown based notes app integrated with Git. (I'm the author)
On it. But not this month. The underlying technology's web support is still in beta (Flutter).
Also, sadly GitHub and GitLab only have all/none access to private repos. OAuth access to specific repos isn't a thing. So Desktop support is more important for me.
The killer feature I need is a share target so I could select a snippet of text, hit share, and paste it into a particular note.