Very interested in your thoughts on the Waveshare MK20. It looks like it could be useful with all sorts of applications, especially music apps and Cantabile. It is not too expensive, but there is not a lot of detailed information on it, in particular on the supporting software, and how easy it is to configure for someone like me who is reasonably technical but not a developer, although I have some scripting skills but little experience of these devices.
I’m following this thread and the related Thoughts on a simple keypad controller thread with great interest to see what conclusions you come to.