Listing packages installed by flake

I have a flake which I have adapted from the configuration used by Misterio. I have reached the point where it builds the system configuration, but fails with an error message:

error: collision between /nix/store/kw6m05qs8017fxq712gb6gwl3vvl4zfg-swaylock-1.7.2/bin/swaylock' and /nix/store/jsbvyyidlvgiz7jr2ihld76d2nga2b01-swaylock-effects-1.6.11/bin/swaylock’

Looking through the configuration, swaylock-effects is explicitly installed, but I can’t see any reference to swaylock itself. Is there a way to list all the packages to be installed without actually going through the process of nixos-rebuild? I want to narrow down my search to find what is pulling in swaylock

I don’t expect anyone to browse the code, but just in case the repo is here