I'm surprised, speaking as the maintainer of Krita, to have a first video review already: https://www.youtube.com/watch?v=D7oFUmVfiww :-)
As this is only about Android I thought of promoting my take on this problem. In fact I released a small program I use to take handwritten notes via iPad on my Linux system just a few weeks ago. It works on both Android and iOS and basically turns these devices into graphic tablets. You can take a look at: https://github.com/H-M-H/Weylus