GPS Protocols is a companion app for the GPS Transfer app - https://play.google.com/store/apps/details?id=com.michalbures.garmin.transfer
It connects to your Garmin GPS and reads from it a list of supported protocols. You can then use this list to find out if your Garmin GPS is currently supported by GPS Transfer app. And in case not send this list to me, so I can implement your protocols.
For further information see http://bures.io/products/android/gps-transfer/
This app requires no permissions.