This is not technically possible… vehicles differ enough that it would require a one off engineered solution for each individual vehicle. Especially older mechanically injected diesels or carburetor gasoline engines which have no electronic engine controls- a a speed limiting device would need to mechanically intercept the throttle linkage, which is designed and attached differently on every vehicle.

Moreover, GPS technology and mapping metadata aren’t accurate enough to reliably tell which road a car is on, or what the speed limit actually is. I use google maps to show the speed limit while I’m driving and it’s frequently wrong. Imagine if they are on a freeway but it pegs them as being on a parallel frontage road with a speed limit 45mph lower? That would be a major hazard.