Oh, if it's a trackpad, it might be unreasonably large for a phone, I suppose it would significantly increase the thickness and bring too many changes to the case. However, maybe sticking a mechanical or optical trackpoint somewhere on the right of the keyboard would work with minimal alterations. I am assuming there would be abundant space in the keyboard half, since all keys could fit in the Moto Mod and this one will be bigger due to the screen size, with no particular need to increase the size of the keys (unlike the GPD or Gemini which are meant for full-hand typing).