I use different Garmin and Tacx products. My main watch is a Venu 2.
When I Zwift (cycle indoor) I use my Tacx Flux S paired to an Apple TV.
I need to use an arm HRM as chest belt do not work well.
All my Zwift activity is immediately uploaded in Garmin Connect.
During the activity I still wear my Venu 2 without starting an activity as it otherwise would double record. I cannot connect the Venu2 to the Apple TV as there are limited Bluetooth connection available and the Venu2 recording is not precise enough for racing.
Unfortunately the Hearth Rate data from Venu2 overrides the activity data causing a whole lot of wrong data in Garmin Connect:
Intensity Minutes
Average HR
Max HR
Interestingly enough the active calories are correct.
It would be very useful if I could select Indoor HR to be primary when available.