Ipad sidecar with touch
This is the one feature that could be provided which isn't. We are given limited gestures, however not full touch capacity with the iPad in sidecar mode.
Because of this I use my Wacom graphics tablet, which does support both touch and stylus
I also find myself reaching well as my surface device before my iPad for this purpose too, before I ever reach for my iPad.
This is a real unfortunate oversight and hamstrings the iPad even more than it should be. It could be the portable monitor of choice but only reaches 80% of its potential, like it does in many ways. Not because of hardware but software.
It would be fantastic if this was rectified in the next update, if it was I would likely use my iPad in preference to those other devices when I need to scribe.