Related, I saw someone using their Apple Pencil with their writing hand hovering above the screen. They weren’t aware of palm rejection, thanks to crappy experiences from other devices and touch based stylus use.

I've never had the palm rejection work on my ipads, sadly, so I too have to use a stylus with my hand hovering, or else I get weird lines and mis-clicks on various UI elements.

The Apple Pencil generates its own signal separate from touch. A stylus does not. Palm rejection is basically ideal with an actual pencil, but not ideal with a touch stylus.