Is this internal/personal code or is a significant part forks/mirrors where you have external upstreams to sync with? Are we talking dozens, hundreds, or thousands of repos?

Are we just concerning/limiting ourselves with local workflow on a single workstation?

Monorepo until there’s a true need for multiple repos. Note that monorepo is not the same as a monolith, one can have multiple “services” in a monorepo depending on the language and toolchain.

What do you mean by “need attention”? What problem are you actually having?