The Toyota nav system in my 4th gen has a surprising number of dirt roads in it. Almost all of them in Colorado and Utah in my experience so far. It's useless for navigating, though.
I have a PLB for emergency signaling. It's more reliable than SPOT or similar devices for calling for help, and there's no subscription. The downside is there is no messaging option, so it should only be used as a last resort.
Compared to SPOT, a PLB transmits with higher power, and it has three ways to find you. First satellites can estimate your position within about 1km using the Doppler effect from the signal it sends out. Then if it can get a GPS signal it will send your GPS coordinates to the satellite. There is also a short range radio signal it transmits so rescuers can find you from the ground or the air using direction finding techniques.