First we start by creating a wineprefix and installing our prerequisites from terminal:
WINEARCH=win32 WINEPREFIX=/home/$USER/GarminExpress winetricks dotnet452 vcrun2010 corefonts
WINEARCH=win32 WINEPREFIX=/home/$USER/GarminExpress winetricks win7
Note: You will be prompted during the setup for .NET installation just hit next and finish. Also, I like to seperate win7 after the prerequisites are setup to make sure the wineprefix runs in Windows 7 mode.
With that out of the way we need to download and install our GarminExpress.exe Setup executable. I downloaded mine from https://www.garmin.com/en-US/software/express
Run the GarminExpress.exe file in our wine prefix
WINEPREFIX=/home/$USER/GarminExpress wine explorer /desktop=garmin,1366x768 /home/$USER/Downloads/GarminExpress.exe
Note: If you downloaded the GarminExpress.exe to another location replace it above
Modify your shortcut to be the following command
WINEPREFIX=/home/$USER/GarminExpress wine explorer /desktop=garmin,1366x768 ‘/home/$USER/GarminExpress/drive_c/Program Files/Garmin/Express/express.exe’
Upon Launch you should see this screen which should recognize your Garmin device
I read somewhere that the watches can be a bit finicky. MTP seems also not be the most reliable. I think there is also a fuse implementation for MTP, which you could try instead of gvfs.
The dialout group would only help for devices connected via serial.
Are you able to log into your Garmin Connect account within Garmin Express, when you connect your watch? Or don't you get that far?