OSMAnd+ and Viewranger will both allow you to create a GPX file containing a Route (and presumably Waypoints, and Tracks recorded in the app, though I've not had reason to experiment with those), which I've used to good effect mid-tour before. No idea how you'd get that onto a Bolt, with a Garmin you just plug it in with an OTG adaptor and copy the file across to the USB-storage device using your file manager app of choice.