piggybacking off @ejoyce, I’ve just checked the postmortem for the second lady thalia game (at least I think it’s the second), and @encorm brought up an article on how to use vscode+github for collaborative projects
if you don’t mind learning a new story format, from memory, @smwhr has created a dendry starter pack that claims to let you edit the source files directly from the browser. Full disclaimer though, I haven’t actually used the starter pack myself.