The PE waffle is a good, maybe even excellent choice for granite tile
underlayment

Cork is also a good choice

There are several other engineered products that work well.

Sound reduction is a major goal in addition to decoupling the tile from
the slab

Again, I'll have a good talk with my contractor about how we approach
this problem, and I will push hard to get the slab poured before
mid-July, so that we get 45-60 days of slab cure time before the tile
gets installed.