This may seem like a joke but in indev minecraft actually had this mob

does it count as a mob if that mob was removed?

Technically yes because it was a concept but didn't make it to the game

whoud the zombie pigman count?

yes, they have been swapped into a mob called "Zombified piglin" in the 1.16 Nether update.

yeah i know

its on of them test mobs that was removed before it was put into the game.