Software defined USB port (Raspberry Pi pico RP2040)
That's freaking awesome. For those unaware, the RP2040 microcontroller has several Programmable IO (PIO) cores, which are essentially standalone state machines that read/write directly from memory to the GPIO pins. Unlike bitbanging the pins with the CPU, you can implement much more timing-sensitive protocols while reducing CPU usage at the same time. There's demos of people implementing VGA out, digital audio, all sorts of interesting protocols.