I leverage git submodules and avoid the same pitfalls of monorepo scale hell we had 20 years ago. Glad it works for you though. I feel like this is the path to ARR until you need to scale engineering beyond just you and your small team. The good news here is that the author has those domains segregated out as subfolders so in the future, he/she could just pull that out into its own repo if that time came.

Still adverse to the monorepo though, but I understand why it's attractive.