Is there a reasonably easy way to add a touchscreen? I can find rather involved/inventive examples, but nothing too straightforward.
If you’re using Ropieee, you can add the official 7-inch Raspberry Pi Touchscreen hardware. Ropieee is compatible with the Digione sig, you may need a new case though.
Check this thread: Archimago Builds a RPi Touchscreen with Ropieee.
I agree that ropieee should work. Its the case that i am I haven’t figured out. The case in the linked article does accommodate the digione sig, as far as i can tell.
In follow-up, I followed the instructions posted elsewhere by Dave Hamby https://retired-moocher-dave.org/2019/04/04/allo-digione-gets-a-face/
This specifically includes the Allo digione in the mix.
It worked very well - going to use a simple pimoroni case/stand, which doesnt try to enclose all that is going on behind the display.