Isn’t this the other way around? I think ERG mode over Bluetooth is supported over the mobile apps, but not the desktop apps (macOS at least).
Last I heard there was some plan to merge how the Bluetooth connections between desktop and mobile work? It would be good to get an update on this if/when it gets updated.
My use case is the Netflix app on iPadOS doesn’t support split screen so I end up having to use my phone to run TR and have Netflix on the iPad. TR on the Mac running over ANT+ = dropouts and Bluetooth doesn’t work.