We open sourced my team's project a few years ago ( https://nomulus.foo ) and it was a substantial amount of work. There's everything you're saying plus a fair amount of engineering to get the darn thing working externally; we were built/hosted within the Google monorepo which is obviously not externalizable. And you end up spending lots of time writing documentation that you hadn't ever gotten around to when it was just a project being worked on by a handful of engineers all sharing adjacent desks.