If you add code to Github and host it on Vercel, isn't ownership still yours?
Don't know much about Vercel, but I'd be skeptical.
I think it'd be an improvement over this project to make those dependencies optional. For example, if I wanted to self-host. I'm using NetlifyCMS for a project and I agree with others that the whole space could use a bit of innovation.
Self-hosting would be awesome indeed, but I think doing it would be quite complicated because of the authentication part, which is needed to push changes to a git provider.
https://www.netlifycms.org/docs/external-oauth-clients/ https://docs.gitea.io/en-us/oauth2-provider/
NetlifyCMS allows you to define your own backends, and Gitea now has OAuth2 support. Should be able to adopt a similar strategy and allow Gitea to be used as a backend.