A tweak that enables Quick Notes feature on iPad Air 2 and iPad mini 4 running iPadOS 15... because Apple wants you to buy a new iPad.
And if you see in the source code, there is an attempt to enable the feature on iPhones. You'd be surprised that it worked, but the Quick Notes window is just too large to be usable - at least on my iPhone SE (N69u).
I do not have the mentioned iPad devices to test this so special thanks to @Ezekiel1998 for putting up with my trials-and-errors.