Btw, Macbook's touchpad can be used with a stylus intended for a phone. (And probably other modern touchpads can too.) Specifically, you can conceivably write or draw if you enable double-tap-and-drag for dragging.

Apple's Preview app allows drawing with the touchpad without double-tapping, to sign on a PDF. Presumably someone could make an app that would switch to such a mode system-wide on a hotkey, and dialed down the sensitivity.

In the demo, I used the trackpad on my Macbook Pro. However, if you want to write, I think you may need a stylus.