So, I have another question xD Is there any way I could increase the number of items my pets treasure chests can hold?

Magical Keepsake Box

They can be found in the millionaire center for 150k they can increase the size of a treasure chest by giving 1-3 spaces randomly.

Oh, okay thank you, but how much can the treasure box hold? Is it like, unlimited? o.O

It will give you between 1 and 3 more spaces.

This Cash Shop item (you can buy it with $5 USD or sP) will give you 10 treasure spots, but the Magical Keepsake Box works out to be way cheaper