Posting a learning here in case it helps others. I bought a bluetooth speed sensor (BBB BCP-65), installed it and went to bluetooth settings to pair it to the ipad, but the ipad could not see it. Blue light was flashing so it was transmitting. Tried my iphone and another ipad, but none could see it in the bluetooth list/settings.
Did internet search expecting lots of complaints about that device and bluetooth, but none. Strange.
Was about to take it back to the shop, when a mate at work said make sure Zwift has bluetooth enabled in permissions, and try seeing if Zwift can see it. Wound up permissions had Zwift access to bluetooth turned off. So turned it on, Zwift saw the transmitter, and were off to the races.
But this is the thing - the ipad/iphones still don’t bring the sensor up on its list of bluetooth devices.
It winds up that the list of devices are just ones that the ipad/phone pair with. The speed sensor just sends out a ping that the ipad/Zwift can “hear”, but it never actually pairs.