The technical requirement I see as a prerequisite would be support for the Precision Touchpad standard. That's a major part of the magic inside Mac Touchpads. It's a shame there isn't that many external Precision Touchpad hardware. Users would pay a lot more attention to touch if so. That said, at least there's a Windows Precision Touchpad driver for the Magic Trackpad 2:

https://github.com/imbushuo/mac-precision-touchpad/issues