I initially had thought of using a rotary encoder, but not as a source selection, instead to help navigate menus as well.
In my case I have a small 5" touchscreen, which from an accessibility standpoint isnt ideal to access some of the menu options. I’m modifying the CSS to make it a bit better (buttons larger / out of the corners etc), but a rotary encoder that would switch the cursor/focus between the screen buttons and allowing you to “click” on them might be better.
I liken the approach to say a car stereo, these days they all have touchscreens, but often also have a rotary knob to switch between menus as well. My family truckster (BMW X1) has a large knob in the centre console that makes this sort of navigation really fast.
Food for thought anyway, I’ve gone with a pure touchscreen myself for now and will spend more time making the theme/css more small-touchscreen-friendly.