Compatible with iPhone? The iPhone thing itself gives you a mesh to use i believe. You just need to re-shape the base to fit your needed face. Which is easier than applying morphs later for all 32plus things.
I think maybe blender has a function (more likely an addon) to transfer morphs. Either way, custom work.
As far as the mannequin goes, unless the marketplace guidelines changed again the skeleton nomenclature must follow the default mannequin skeleton.
Paragon characters may be an exception to this naming wise, but re-target fine. Sockets shouldn’t matter. You can really save an added item? Persona being just a preview. You should likely close that and the animation before retargeting.
Some programs have different options to support different engines. Anyway the main difference in all of them is the placement of the twist bones and their parenting.
What matters more than names is Rotations of the bone (starting pose), and its hierarchy.