Availability check to only include physical inventory

I would like to configure SAP to only consider physical inventory only when doing an availability check. This allows a manufacturing facility to release production orders to the floor with confidence.

The process I would like to use is:

MRP creates planned demand

ATP checks physical inventory for availability (unrestricted inventory - already confirmed inventory)

Release orders to manufacturing floor (All production orders upon release do an availability check via configuration (OPJK))

Repeat

I have checked tried a lot of different combinations of OPJJ without success.

One of the problems, I think, is that the component that SAP says is available is a make part that has a 0 lead time.

With a physical inventory check only, lead time should not be relevant.