Yes, it definitely can be done this way. With some elbow grease, it is possible to design a custom display object graph with its own child-parent relations and matrix transformations, and use nme.display objects just for final "rendering" (keeping them as siblings of one parent). It's just a pity that a perfectly good nme.display object hierarchy is so inconvenient to use just because of inability to set an arbitrary pivot point.
I was looking for the answer to this question as well. To the best of my knowledge, the standard display library doesn't have this option. It is designed to match flash display list, and in flash pivot cannot be set in code. Starling seems not to have this limitation, but it doesn't compile to native code.
If anyone could prove me wrong, I'd be really happy as this is one of the two major reasons that stops me from using HaxeNME (the other one being inconsistent feature support across targets).
I checked the source code of both nmext and nme-extensions trying to understand if in-app purchase functionality is production-ready. If I understood it correctly, both extensions are very much work in progress and Android IAP functionality is completely missing at this point. Please correct me if I am wrong - I am very new to NME.
Could you please tell me if
(a) there is a turn-key solution for IAP in NME (I'd guess - no)
(b) the IAP extensions will be developed further any time soon
I know it would be better if I could contribute to the project rather than asking this question, but I am afraid my C++ skills are rudimentary. I have much more experience with Java (including Android) than with C++