Hardware-wise, I think I'm reasonably happy with what I have – at least it's more than sufficient as a prototype for testing. What I need now is the software. I have tested the device with CircuitPython – I have even written a GIF decoding library in pure Python specially for this – and I'm confident this can work, but not with CircuitPython. So the next step is to get the the firmware for this working.

I can use the TinyUSB library to expose the filesystem over USB – it's the same library that CircuitPython is using, in fact. And I can use a super-optimized GIF library written by @Larry Bank. That should get me the minimal functionality. I can then also experiment with sleep modes and touch and all that stuff.

The problem I am facing right now is setting up an environment for development for the SAMD21. I will probably start with Arduino, because that is already mostly ready out of the box, but there is still some work with that, that I currently just can't get myself started on. So until I get that going, the project is on hold.