> For example, Cmake can use vcpkg to install a package but then I still have to write more cmake to actually find and use it.

I have this solved at our company. We have a tool built on top of vcpkg, to manage internal + external dependencies. Our cmake linker logic leverages the port names and so all you really do is declare your manifest file (vcpkg.json) then declare which one of them you will export publicly.

Everything after that is automatic including the exported cmake config for your library.