What is the function of WLAN_ANT_CTL1 and WLAN_ANT_CTL2?
These are for external RF switches eg to implement antenna diversity. These have to be set up with the nvram file. You will likely have to work with Murata/Broadcom to determine the correct settings.
ie, to use these you need the volume required for them to provide support for this.
Sounds like a feature that 99% of IMP003 users will not use
Correct, but it’s there just in case.