Yeah most 64 games used scaled sprites for various objects like trees and sometimes even chars. This is why I think on the HP Prime, using the Triangle command to generate basic terrains or walls you wouldn't really need that much 3D rendering for the rest, although detecting if a sprite is in front of or behind a wall might be trickier.

Well, even the (normal) DS does this, and many older games on both computers and consoles also do this. This is mainly used for objects far away or in other cases where it isn't that visible though, but they do use it. Mario kart n64 and other games of that era just did this to a much higher extend than now though, since currently it's pretty much only used to render particle effects.