Well, zombie thread or not, I have a psudo-helpful, partial answer for this - and even then, this relates to older Clean Republic-era Hilltoppers with 24V/250W 8FUN hubs; I can't speak of the current ones:

If you're willing to re-wire the system to work with an aftermarket 24V brushless motor controller, you're limited only by the functions of that controller. In other words, with enough DIY know-how and soldering, you can modify the Hilltopper to suit more than a few needs.

Case in point, I recently picked one of these up on eBay dirt cheap and converted it to pedal assist with a $10 (sometimes $26, depending on the supplier) 24V motor controller from Amazon and an aftermarket PAS sensor. That same controller has a connection for a throttle, but I don't know if said connection results in "constant on" or not. Didn't use the original battery either, so there's not really much of the Hilltopper left, but it did perfect on its maiden voyage today. Build thread: The E-Spin: Converting a retired dockless bike into a pedelec

Mind, the motor controller above is as basic as it gets. You can't adjust the amount of the assist from the PAS and there's no LCD. Others are more fully featured.

-Kurt