Initially the PiHole module was supposed to provide an option to expose rootless PiHole on privileged ports s.t. the user does not have to find out/decide how to do it herself.
However, it seems to be out-of-scope for flake which should provide a rootless PiHole container.
Further, any decision taken on how to achieve this could limit the users choices for other system configuration options.
Inestead options for making PiHole available on priviledged ports should be described in the Readme and maybe in example configurations.