[ashishb]

I have worked at Google and have built multi-language outside Google.

1. Have some concept of visibility restriction e.g. Go language has internal package.

2. Ensure that every single package has a command to build the code.

3. Ensure that CI builds all the packages that changed our impacted by the change in a given pull request.

These three steps are mostly sufficient in having a monorepo. What you get in return is high code consistency and code visibility for the whole team.