Máximum number of active bluetooth connections

Using CIQ's BLE, the limit is 3.  An exception will be thrown if Ble.registerProfile(() is called and there are none available.  You can also use Ble.getAvailableConnectionCount(), 

See https://developer.garmin.com/connect-iq/api-docs/Toybox/BluetoothLowEnergy.html

in registerProfile()

"Registration can fail if too many profiles are registered, the current limit is 3."

Same on all devices and has been that way since it was introduced a few years back.  It may have been mentioned in the breakout session for this, but I'm known about the limit of 3 since that time.

https://forums.garmin.com/developer/connect-iq/b/news-announcements/posts/adding-bluetooth-connectivity-to-your-connect-iq-projects