Digi-Key Part Numbers:
The datasheets for these parts state that their support for GNSS is “optional” suggesting that there are manufacturer’s part numbers with and without GNSS support. Do the modules you stock include GNSS support?
I would understand the idea of “optional” GNSS function to mean that it is not necessary to implement it in order to use the other features of the device, rather than in the sense of some part numbers including the GNSS feature while others do not; there’s a good chance that using the GNSS function requires an additional antenna.
I do not have access to the complete documentation at this time however, so it’s possible that this interpretation is incorrect.
You are correct, an antenna is required to be connected to the module for comms and with GNSS support an additional antenna can be connected for positioning… some variants of the module have support internally for GNSS and others do not.