we are frequently using the Power bi iOS App and communicating with each other using the commenting function. It would great to work here with the Apple Pencil to draw and write in the comments. Unfortunately, today the sensitivity of the drawing is much to rough and so drawing with finger is still more accurate.
Are you refering to the "annotation" capability (that takes screen capture and let you add free hand drawing) and then share it with others using external apps? or to the commenting feature that is Power BI interanl only communication channel?
In any case, at this point integtating with Pencil is not in our roadmap.