FWIW, as a Xoogler, I find I can get pretty far with 1) abseil, 2) grpc, 3) protobuf, and 4) groping around in every open source Google project to find the thing I need (for example, until recently, Cord could be found in random projects but not in abseil). I don't know what it's like for ex-bookfaces but this gets me a good way to my goal, and as a bonus I get to use stuff I wasn't able to at G, like C++17, or io_uring, or even jemalloc.