At the moment, Bing, Google and Openstreetmap can be chosen as map for creating a course (https://connect.garmin.com/modern/courses).
Especially for MTB and/or gravel cycling, OpenTopoMap would be best (https://opentopomap.org). As Openstreetmap is already a valid option, OpenTopMap may be easy to implement and definitely helpful for offroad cycling! ciq.forums.garmin.com/.../1327758.png