Digital Pen settings, option for keyboard toggle between two presses eg. B and E in photoshop

Hi, I am new to Huion. I've had a couple of wacom tablets in the past. I suspect that Wacom's eraser tip is parented hence no one else using it. What I would like to suggest is an extra option in the pen settings.

As well as keyboard Key, it would be nice to have a toggle between two key option. So in applications like Photoshop you can press once for [B] to go to brush mode, press again to enable say [E] to switch to eraser. That way you can use the same button to toggle between the two most common states.

The above is one example, but basically let people define their own toggles between whichever two features they like. It would really make digital painting a lot more straightforward. 

Thanks.