I'm bringing this project back from the dead, now that I have learned a bit and got new ideas for it. I already wrote about a solution for the battery problem — have the battery on the other side of the wires, on your neck. I'm going to go with that, but since the #Electronic Barrette Hub is not ready yet, I will use a regular battery holder.
The other innovation is using a thin PCB, and a PCB USB socket — that lets me make it really thin.
I slapped together a PCB design with those ideas incorporated, and it arrived today, so I assembled it:
It's flashed an ready to be programmed. Next step is to compile a version of CircuitPython prepared for it.
The last innovation I have is software: I no longer need to use BMP files, as I wrote a Python library for reading GIF files. It's probably not fast enough, but there is one more possibility — perhaps I could include a C library that was recently created for SAMD21 for playing animated GIFs as a CircuitPython C module — then they should play at native speed.