Ok so pummeling Chargeis currently worded as the following;
You can charge and make a full attack or flurry of blows at the end of your charge as part of the charge action. You can use Pummeling Charge in this way only if all of your attacks qualify for using Pummeling Style against a single target.
Jani Rush says;
While using Janni Style, you are always considered to have a running start when jumping. Further, if you jump as part of a charge and make an unarmed strike against the designated opponent, a hit allows you to roll the unarmed strike’s damage dice twice and add the results together before adding modifiers (such as from Strength) or extra dice (such as precision-based damage or dice from weapon abilities). The extra damage dice are not multiplied on a successful critical hit.
Would these two feats together cause all the dice from pummeling charge to stack or just the first damage roll from pummeling charge?
Unfortunately the only other post about this was made by me 4 years ago which yielded no clear answer, and pummeling charge has since been errataed further than at the time of the original post.
Like most things, unless otherwise specifically stated, it's the first attack.
But yes they work together for the first hit of your pounce attack.