Pets are a missed opportunity here and in POE. Pets should do something. Dont make it gotcha like Torchlight Infinite but each pet class should have an ability. As long as 1 pet from each class is earnable in game then you can and should sell at least 10 from each in the store. This is something that needs to be done.
Quick examples:
Flying Carpet - Magic Class - Get a sorc to level 60
Hellhound - Infernal Class - 2000 Cinder mythic rarity helltide chest
Ghost - Corporeal Class - Kill 400 ghosts
Rabbit - Herbivore Class - Gather 600 herbs.
Flying Gold Carpet - Magic Class - Shop
Baby Hellhound - Infernal Class - Shop
Spectre - Corporeal Class - Shop
Panda - Herbivore Class - Shop
Magic Class: fix later
Infernal Class: 15% higher cinder droprate. Enemies burn 15% faster.
Corporeal Class: You are unhindered. You gain 10% movement speed.
Herbivore Class: 25% Chance for herbs to drop in pairs. Gain a burst of speed after harvesting herbs for you and this pet.