shrunk

$ nix-build -A shrunk
/nix/store/cllwnkph7kdj676p33kfff9rdwfv6dg8-linux-5.4.122-shrunk

This is a subset of the module tree produced in the kernel derivation. The subset is specified by the rootModules argument in stage-1.nix.

That subset is packaged as part of the initrd.

The lis of modules can be extracted with:

$ nix-instantiate --eval --strict -A root-modules