Possibly not “companion” per se, but Every Door is available for iOS and MapComplete can run in browser. Go Map!! can provide more detailed editing.

BRouter and other routing engines can use attributes like surface and smoothness (and probably width) to calculate routes.

Are you referring to smoothness=bad or a narrow width? (I’m guessing you’ve been using StreetComplete to specify each.)

Yes, OsmAnd: https://osmand.net/docs/user/navigation/auto-car/