thanks everyone for your replies. ndi and yams work indeed. much appreciated. however i am still kinda intrigued about the sidecar option because it actually semi-works.
here are two screenshots for the same file with the macbook and ipad connected via sidecar but different screens assigned as "secondary". when the ipad is assigned as the primary screen or "display 1", everything works smoothly, I can use my ipad as my main display and control the scene while the macbook screen is used as the second display.when ipad is display 1 and macbook is display 2
however, when the ipad is assigned as the second display, the ipad screen turns white instead of displaying the stage it's assigned with.when macbook is display 1 and ipad is display2
sorry if this was already clear, but I wanted to make sure that I was able to explain the problem. i'm risking repeating myself because it seems to be a minor problem that might actually be a bug that could be solved with a tiny little patch?