project budget control for Project Inventory PR

Dear Experts,

We have two queries:

1) Why there is no Oracle solution for proj budget control for Inventory Proj PRs/POs? why only expense commitments transactions budget control available in Oracle?

2) So far, we dont have PJM module, but if we implement, can the INV Proj PR/PO be seen in PSI as commitments until receive/Accounted in AP level?

3) If yes for point2, then can we use Proj budget control for Proj Inv PR/PO?

4) if no for point2, then how to achieve with a customization project budget control?

In our client's normal business practices, Inv item and its key parts are the most important assets and  should be controlled in project Capex budget with quantity maintenance before it is available for using.