I’ve also picked up several pico based devices (Adafruit has a neat usb dongle with a couple rgb leds and some capacitive pads for buttons that’s about 6$) and yes they’re all micropython or some flavour thereof. Basically all it runs is a python interp (as opposed to an RPi that’s got a Linux kernel and env); someone with arduino or other µcontroller experience might could look at porting but given the resource constraints of the hardware I don’t think Perl is going to fit well (primarily RAM limits would be my fear).

Edit: not strictly a pico (but runs circuitpython) and it’s 7$ but https://www.adafruit.com/product/4870 if anyone is interested. Also note there’s all of 32K of ram on this thing.