devtrackers.gg
The pet already has it, just not the familiar override. Hopefully they will change it to match Telos pet soon though.
I've changed it to work on overrides, but also added 'most normal mechanics active' to the examine for those who haven't done hard mode but are jammy enough to have the pet.
Shouldn't take long to make it to the live game.
Edit: Just saw comments about Nipper demon override, added that too.