Hi Vishal,
You can create a customized report using datasource :SCMMSDVV02(Material Supply and Demand List) which provides information for all types of Proposals in one report putting filter on field Category IDs.For Purchase Proposals , use Category ID as 1 and 2.
Please check this knowledge base article:
2187133- How to Get Planning Proposal Details in a Report.
2. You can also check Purchase Proposals info via Supply Control Workcenter -> Process Purchase Proposals View.
I hope this helps.
Regards,
Kopal Upadhyay