In order to speed up the build a little bit, we can try to avoid protobuf compilation. This can be achieved with flag --incompatible_enable_proto_toolchain_resolution with a help of https://github.com/aspect-build/toolchains_protoc or with a nixpkgs protobuf binary, registered through specific toolchain.

Maybe even running with a simple --proto_compiler=@nixpkgs_protobuf//:bin/protoc would be enough.