My Garmin zūmo XT seems to have most trails and forest service roads I've tried on it. It also has satellite view and topographical maps for when you're riding on something that it doesn't recognize. I think the Garmin Montana series is a more popular choice for ADV riders, but I've gotten by fine with the zūmo XT.
For cellphone apps here are a few I've used and found some value in:
https://www.gaiagps.com/ - have planned backpacking routes with this in advance and saved as offline maps and printed to paper, could do the same for moto trails
https://www.alltrails.com/ - use this regularly for hiking, have used it for some 4x4 trails
https://www.onxmaps.com/ - don't have a lot of experience with this other than using it to identify public vs private tracts of land, a few friends use it as their primary trail riding app
https://www.rever.co/ - This was included in my "Rider Plus Membership" for RevZilla, CycleGear, and J&P Cycles. It is still very new and clunky for both on-road and off-road use, but it has "social" features for recording your ride and generating a route report. It's easy to build either on-road or off-road routes from the phone screen by selecting up to 5 miles of segment at a time. For on-road riding it has data from Butler Motorcycle Maps where it highlights segments of road that have appeal for motorcyclists (scenic views, twisties). The "Discover" feature is nice if you don't have an agenda, but definitely have to watch out for it trying to put you on fast roads even with "avoid highways" checked.