How to get the max assemblable units without Purchasing

Hello everyone,
we are a quite small company and often we face with the question “how many devices/product we can assemble without waiting any delivery/receving any order”?
Essentially I would need to have a similar to the MRP functionality that consider all the sub-components for its BOM (+sub BOMs), calculating the max value without any purchasing.
There is any similar functionality already implemented? If no, any tip about how get that value?
Many thanks, Kind Regards