Here is a fairly complete forensics of NYS non-resident wage an RSU tax code and forms. The reason lacking a simple answer is because how convoluted the explanations and forms are.. The actually logic buried in tax code 20 years ago is reasonably clear.
https://www.bogleheads.org/forum/viewtopic.php?p=8690416#p8690416
To do the actual NY workday accounting, I had to use an AI. Without it, it'd be manually making a day by day log like a time sheet. Using AI isn't trivial but maybe good to generate the initial daily log to hand adjust.
https://www.bogleheads.org/forum/viewtopic.php?p=8690454#p8690454
