AP_Periph Passthrough

I have a CUAV Neo 3 Pro GPS that uses DroneCAN to connect to my Holybro Durandal. Right now i am trying to passthrough the GPS via DroneCAN to my PC, to access the uBlox M9N for firmware update, and general usage of u-center with it.

I looked around and saw the MAVSerial Pass, which is supposed to passthrough the GPS to localhost:500, but only if the GPS is directly connected to the flight controller, and not using DroneCAN/AP_Periph right?

Looking further i saw the Here 3 GPS can do what i want, but they implemented it by using a parameter to set the connection mode to the GPS (passThrough = 0: standard, passThrough = 1: u-center parameters, passThrough = 2: u-center firmware update). More about that here:

Unfortunately my Neo 3 Pro does not have that parameter, and none of the parameters hint at anything similar. I updated the Neo 3 Pro to the latest AP_Periph 1.4 version.

Any ideas how to get the passthrough going?

@rmackay9 @tridge