Do not waste your Polished Pet Charms on items that increase your maximum number of pets! The cap has been entirely removed in Patch 9.1, which means you can instead save and spend them on something meaningful!
In Chains of Domination, there is no longer a cap on the maximum number of pets you can own, which means you can have unlimited pets. However, they are still limited to 3 of each species.
This means you no longer need to buy Shattered Pet Portal Interdimensional Pet Portal and Broken Pet Portal Pocket Pet Portal that cost 1,000 Polished Pet Charm Polished Pet Charms each.