Hmm. no the nav system adds no extra info. If you have the screen then you do have the same info the Prius gives. I know that the basic HiHy doesn't have a screen so it's harder to tell what is going on. It could be that the Prius and HiHy display works differently I don't know.

The goal when accelerating is to use only the ICE as much as possible (i.e no battery) and also to avoid using the ICE to charge the battery as this is inefficient for fuel efficiancy (FE). it is also inefficient to have the ICE charge the generator and have the generator push the wheels (this can at least be done in the prius). When I accelerate I try to find a bad where I use the ICE only and all it's power goes to pushing the wheels forward not to the generator (or the battery). It's not a perfect science (esp. at low speeds) but you can find a pedal position that makes the ICE spin the wheels mostly.

I did find that this improved my FE overall. Hope it helps