A few years ago, I tried to turn a Pi Zero into a ‘synthetic USB stick’ – where you’d plug it into your laptop and it’d appear like an ordinary flash drive, but the program on the Zero could intercept reads and writes and dynamically generate content. Like a FUSE filesystem, but as a piece of hardware, sort of.
So you could edit a Python file on your laptop, save it to the USB drive, and then the output of your Python code would magically appear as a sibling file on the drive; things like that. I thought it would be particularly cool as a way to get some dynamism and programmability