During lunch a friend mentioned that you can just supply a HTTP URL to vim on the command line and it would use curl to download that resource and allow you to edit the content. I jokingly asked whether if you enter :w it would then issue a HTTP POST back to the origin which is of course ridiculous.
It issues a PUT
@conorh Next step is figuring out that Finder has WebDAV support since forever and you can effectively do that with literally any macOS app.