As it happens, I'm building "Github for Journals".
I pivoted away from attempting a crowd source review approach with a reputation system to trying to support journals in going Diamond Open Access.
But the platform I've built supports co-author collaboration, preprints and preprint review, journal publishing flows, and post publication review - all in a continuous flow that utilizes an interface drawing from Github PRs and Google Docs.
You can submit a paper, collect feedback from co-authors, then submit it as a preprint and collect preprint feedback, then submit to a journal and run the journal review process, then collect feedback on the final published paper. And you can manage multiple versions of the paper, collecting review rounds on each version, through that whole process.
It's in alpha, I'm pushing really hard with a short runway to get the journal flows to usable beta while trying to raise seed funding... the catch being I feel very strongly that it needs to be non-profit, so seed funding here is grants and donations.
I'm looking for journal editors who want to participate in UX research. I'm also interested in talking to folks who run preprint servers to see if they'd have any interest in using the platform. If you (being any reader) know any, or have leads for funding, reach out: dbingham@theroadgoeson.com