Good way to build this would be on Radicle
Nostr could work after it's merged with Radicle via "Project Zymogen" 
6.268ɱ | The GitHub cure: Radicle + P2P + Tor + nostr + Monero (Project Zymogen) · Monero Bounties
Project Zymogen Goal: to potentially create a decentralized GitHub. (You can name it whatever you want, Zymogen is just a placeholder name) Phase I A