Can I import GPX tracks from other apps or sd card without an internet connection?

I use other apps on my phone for planning routes on the fly (specifically apps with slope angle assessment and access to many map sources/satellite photos for ski touring), and often travel/base myself in areas without an internet connection, and would like the ability to upload route plans to my InReach from my phone without requiring an internet connection. It doesn't appear to support the Mass Storage protocol to upload via usb/otg cable like I can with my etrex, so it appears that requesting an improvement to the Earthmate Android app to allow us to do this would be the most hopeful.