Any sugg to build vstis based from sdk projects?

[23fx23]

Im building a synth with sdk from a while but id like to be able to use as a vsti.

all the code rely a lot on c++ but mainly the graphical engine for drawing, user interacting this inteface callbacks , and of course audio out are handled by usine actually.
so thought i would like to try to port it as an independant vsti (unless we get a vst export by that time? :p),
but i m a bit lost where to start with.. had look at juice but don't know..

So what im looking for is what could i use that could remain *relatively simple but basically draw shapes, lines, rects, points ect in a windows, and have touch callbacks for manipulating points faders ect, as a replacement, that would be somehow similar to usine sdk, trying to keep big part of already written code with adapting of course.
any experience/suggs?