I would recommend against using leaf litter from outside as well, because you don't know if it came from a tree in the yard of someone who used pesticides, thus making it possible for the leaves to contain pesticides. Many places ban pesticides now but the ones that used to be used have a verrrryyyyy long half life, so they stick around for a while in significant quantities.

What you could do is use some coconut husk, it kinda looks like leaf litter and it would also help you out in the humidity department during molts.

Congrats on the freaking awesome birthday present btw! I wish I got presents like that lol