I would think TGP or dry solvent would work. Otherwise, I don’t have kids and haven’t purchased/used crayons in a while, but aren’t they wax based more so than dye based? If so, an iron may work.
As an alternate to using an iron, I’ll put some water on a towel and stick it in the micorwave for a minute or so. Gets DARN hot and works awesome on things like wax, candy/sticky food bits, etc. crayon too I’ll bet.