I’m using TD and BigRingVR at the same time 
Though I could let BigRingVR take the control of the workout in ERG mode, by importing the workout file, I prefer to follow the workout on my phone with TD, while BigRingVR controls the slope of the video ride I watch on my PC. TD is connected to my sensors with BT, BigRingVR is connected with Ant+. Luckily, all my sensors have both BT and Ant+ capabilities…
So does Bing Ring have this option of selecting power source and controllable seperately like Zwift does or are you just connecting a power meter to big ring? I realize now that I think using our app with other apps like Zwift, RGT, BigRing, Fulgaz is great solution for most people wanting to do ERG workouts while “watching” those apps. We can likely continue to provide a better ERG experience then they do due to our workout training focus.
I never used the option, but yes, it’s possible.
According to their FAQ:
Is it possible to do BigRingVR rides while another app (eg TrainerRoad) controls the resistance on my Smart Trainer?
Yes, in preferences you can create a ANT+ configuration that uses your Trainer as a power meter, but not as a controllable smart trainer. When creating the configuration, make sure to set the smart trainer to “Don’t use” and set the power meter to the power channel of the smart trainer.
I have two power-meters (one for each of my two bikes), and BRVR has a powermatch function, so I can use the same power profile as when I ride outdoors. And I already have 3 settings in BRVR to use one or the other power meter, or to directly use the one from the HT.
Is that a big hint at ant+ in the near future?? 
The problem that I have it that I can only use ant+ on windows. It isn’t accepted on Apple TV so trying to combine it with a BLE only app is/was always going to be faffy. For me there has to be some ant+ capability from either the TD app or apple TV.
Let’s face it, apple won’t do ant+ anytime soon on Apple TV.
It means I am starting to take it much more seriously My app developers schedule seems to have a little more flexibility coming up as well.
The ANT+/BLE combination is always suggested as a way to run TR and Zwift on Apple TV. In fact ANT+ is almost a necessity to run TR & Zwift.
DC Rainmaker posted an article about running Trainer Road and Zwift at the same time:
There’s two (out of three) options that only use Bluetooth but will depend on your devices. Some of this advice will apply to running Trainer Day and Zwift at the same time.
None of the “Option B” solutions were suitable to me unfortunately.
I don’t have a wahoo bike/kickr
I use my second powermeter for powermatch so that additional BLE channel is taken up.
I have thought about using a NPE Cable or a 4iiii HRM but they were all out of stock. Also they are both around £70 including shipping which seemed a little excessive.