Writing this in the windows express forum because there really isn't any other place to ask it on garmin.com
I am wondering if there has ever been an attempt to write a driver to make the Garmin USB Mode that is available on virtually all Garmin watches and some GPS units, work as MTP
This has been done for some smartphones, bypassing the windows storage mode as a utility, etc.
Their published driver uses "grmngen.sys" "grmnusb.sys" and installs as VID 091E PID 0003
It has a copyright of "walter oney software" which is a well known old windows driver author but it may not be him who wrote it, they just used his code in part.
I assume it is a direct serial interface to the watch.
If no-one shows up who has done it I am wondering to ask it on the xda forum where many phone developers exist and probably know how to investigate.
The idea is to keep the watch in regular operation and also allow it to have power but also move files back and forth from the watch.
A true MTP driver instead of the old "mass storage" for windows would allow this to happen but Garmin apparently is not interested in making such a driver themselves.