Probably the Google-sponsored cryptography library you want to use is Tink, whose maintainers include Daniel Bleichenbacher, Sophie Schmieg, and Thai Duong.
Probably the Google-sponsored cryptography library you want to use depends on the language you're using... Not much point in using Tink if they don't expose a C-api or any other ergonomic form to make Rust bindings.
This is not an official port of Tink, and is not supported by Google's cryptography teams.
Looks like an unusable mess for C++, this seems to be common problem with all of these crypto libraries-- just too many files and too complex of a build system(shocker not everyone uses CMake).
As someone who sometimes uses e.g. FreeBSD, I'll take CMake over someone's hand-crafted Makefile any day.
CMake is the de-facto standard for C++ build systems - its not the simplest, but it does an outstanding job at being widespread and reliable.