Extracting fit files without internet connection

jbergj which device is it? - you should be able to use an app like sporttablet and use ANT+ to get the files onto your phone - I assume that you won't have a PC accessible

If you have an Android device you could also use an OTG cable (like this - https://amzn.to/2HKvl8g) with the cable/charger that plugs into your device. Plug the cable/charger into your Garmin, and the other end into the larger USB end of OTG cable and then plug the smaller USB end into your phone or tablet. Load something like X-Plore File Manager (https://play.google.com/store/apps/details?id=com.lonelycatgames.Xplore&hl=en_US) and navigate to the device in the File Explorer, find the directory where the .fit or .gpx files are and copy them onto your mobile device. You can then import them into any number of apps. Works well for most any Garmin device.

JSRUNNER_ My phone is an android with integrated ANT+ chip (previously Samsung Galaxy S6, now Samsung Galaxy S8+) - I also succeeded with this method using a generic android device with OTG adapter and ANT+ USB stick.

The previous watch where my method was succesfull was Forerunner 910XT, my current watch where I can't repeat this desirable trick is Forerunner 920XT.
My understanding is that between 910 and 920 Garmin switched from transferring activities with ANT+ to transferring with Bluetooth.

Lectrichead Thanks for the suggestion of using a wired connection to explore the filesystem of my watch. This does make the whole transfer a little more cumbersome, but it will at least solve my problem as long as I bring my cables with me at all times.

Thanks both!