I have a throttle but it doesn't control the pas level
You are looking for a way to mechanically set what is a "logic" value? While I know bugger all about electricity, I have some programming experience. Given their price, I would expect 'controllers' to have very simple 'logic' (conditional tests). Code
might look something like this?
If option selected = 1 then PAS = [resistance value]
If option selected = 2 then PAS = [resistance value]
If option selected = 3 then PAS = [resistance value]
If option selected = 4 then PAS = [resistance value]
Otherwise PAS = [resistance value]
Controllers with 9 power levels, obviously will have more incremental increases. To have the PAS level tied to a mechanical device like a potentiometer (which is what I think a throttle is), would need an almost infinitely variable amount of options, unless the potentiometer had fixed 'click points' that coincided with the 5 or 9 levels seen on electronic controllers.
Given electronic controllers are often placed close to fingers where a small finger/thumb movement increases or decreases the PAS level, the potential benefits of a mechanical (twist grip) option for PAS seem negligible, if there are any?