Hey,
Beside the Core sensor, is there other devices that provide body temperature?
Any Garmin watches? Or HRM strap that includes the temperature sensor?
I recently saw these, which indicate they can do HR and body temp, and also that they are compatible with Zwift. I’m not sure how this would work, and I haven’t seen Zwift post anything about them, but they could be a potential option. Of course, they may also be compatible with Zwift in the same way that some spin bikes advertise being‘compatible’. 
I imagine anyone can come out with such a sensor, but I guess the question is if there’s a standard protocol in the signal delivery, or if they’d have to pay Zwift to accept their unique signal?
Ah, possibly! I had not considered only some of the features being available in Zwift.