Reading this and mitchellh's post I was curious about code archival services, and found a few projects.

GitHub has their own: https://archiveprogram.github.com/

Software Heritage is a non-profit funded by UNESCO: https://www.softwareheritage.org/2019/08/05/saving-and-refer...

Although they're mostly the code / commit history, not so much surrounding metadata like issues, PRs, discussions, wiki, etc.