Yes, that's correct, Google invented its own proprietary distributed object store and distributed version control system and distributed Linux-only filesystem and distributed build-and-test-system to work with a single SDLC that its entire company must follow strictly to release anything, just so it could keep using a single repository.
You have no idea how Google solved it. Basically everyone with a Monorepo (except Google) implements it as a cargo cult best practice. Mindlessly copying Google without understanding how Google actually does it.
What's your point?