Sure but then you only have some small portion of the total infrastructure, which adds its own layer of complexity for the people reviewing your changes :P It's all trade offs, is all I'm saying - I honestly still can't decide between the two, although for all companies sub 20 people, I'd for sure stick with a single repo.

If it's a "small" company then I'd expect that one Git repo would do just fine for all or at least most of the code. When I think small, I think ~10 or 20 developers. If you have reasonable hygiene about things like keeping binaries out of your Git repo (excluding consideration of e.g. LFS here) then the whole repo size will stay fairly reasonable. As long as you have one or two Git mavens on your team it should be dandy.

I'd expect to see problems with this approach once you get into the 100s or 1000s of developers. The tooling for this scale of repository isn't as mature.