The end result I'm seeking is the ability to combine the information from wandrer-generated OSM maps with the information provided by this tool. I don't know the technical detail about how OSM works or how this tool works, and maybe if I did the answers would be obvious.
Wandrer.earth allows a user to download OSM maps with road/path shading changed to reflect roads on which the user has previously traveled. These maps are then sideloaded onto the wahoo device (although a different process from described here) and get displayed on the map page.
Obviously this would be a per-user action, but I'd like to explore what would be necessary to make this happen.