Agreed! I picked up an ideapad to use the pen feature for drawing. It's nearly impossible to use in Affinity Designer/Photo. If you go in a the wrong angle or lift the pen too high, you get marks or new boxes under your hand.
Here are some other posts requesting the same feature:
https://forum.affinity.serif.com/index.php?/topic/63156-how-do-you-disable-touch-drawing-on-affinity-photo/&do=findComment&comment=427164https://forum.affinity.serif.com/index.php?/topic/58505-disable-just-finger-drawing/ (This mentions Krita; an open source drawing program that toggles this feature via "Enable Touch Painting")
https://forum.affinity.serif.com/index.php?/topic/51014-option-to-disable-touch-input-on-tools/
https://forum.affinity.serif.com/index.php?/topic/48625-disabling-the-touch-on-the-surface-book/
https://forum.affinity.serif.com/index.php?/topic/30004-pen-sensitivity-with-touch-rejection/
https://forum.affinity.serif.com/index.php?/topic/40151-toggle-painting-with-touch-when-using-touchscreenstylus/
https://forum.affinity.serif.com/index.php?/topic/50407-option-to-disable-tool-input-with-touch-on-windows/
Unfortunately evidence shows that windows does not handle this well (with the "disable touches when using the Pen to draw" feature) on it's own and Microsoft has added software like Sketchbook and Sticky notes, that disable touch and only respond to pen on the drawing surface (These work great).
Hope this is something we can have added. As mentioned above, there is an open source painting project called Krita that handles this beautifully, maybe they can be a source of inspiration.
It's a pain to switch back and forth between drawing and design.
Thanks!
-Ryan