First of all welcome to the forum.
Second boost bottles dont add anything to these china girl engines so do one if you wish but the best engine builders and racers of these ebngine will all tell you a boost bottle is a waist of time and money.
As far as the 1/4 throttle you spoke of these untilize a short pull on the thottle but I guess you could make your own. If you wanted.
Go through this forum and use the search feature, you will find piles of info on performance tuning these engines and what works and what is snake oil like the boost bottles, if someone like the look of having the bottle on their bike that is fine but dont expect any performance gain from it.
Cleaned up ports, a well tuned carb and a good free flowing exhaust will do way more than gadgets like boost bottles on these engines, these china girls will never perform even close to a good Japanese 2 Stroke engine no matter whT you do to it, but there are several things that can be done to improve performance.
Best wishes and again wel ome to our great forum.