I disabled hardware.bluetooth.enable in /etc/nixos/configuration.nix - which I think is sufficient, though I still see various bluetooth-related modules in lsmod. Is there an easy way to avoid loading those (rather than just rmmod’ing by hand)?
Interestingly I had to boot.blacklistedKernelModules = [ "btusb" ];, otherwise it’d just load bluetooth anyway (I guess because it is a dependency of btusb).