Totally bizarre - and I know this subject has been raised over the past.
I recently read that SRAMs AXS app can be connected to DI2 via Garmin Connect.
Tried it.
Yep.
I can look at my rides and all my gear changes, power per gear, etc. etc. via SRAM (ie not Shimano).
So Garmin collects the data on / via the web....so why not show it in your apps?
Makes. No. Sense.