It's not exactly what I think you're looking for, but depending on what you are trying to do, maybe look at hackmd/codimd.
It's more like Google docs meets markdown formatting. It's goal is realtime collaboration but I've definitely used it for syncing todo lists with people.
Codimd is the self hostable version.
Oh, and I think there is a way to have it sync with a GitHub repo too, in case that is useful.