So I've been tinkering with those
$6 Seeeduino Xaiao boards since Amazon delivered on time. This board has direct support for Arduino IDE right out of the little triple-matchbox they come in, plus CircuitPython and even the TinyUSB HID device development project.
Of course, I found the little tin cover offensive, and had to take a peek under one of them.
Nothing exciting; the ATSAMD21G18A processor, a crystal, some passives and a LDO to produce 3.3V from the onboard USB-C (!!!) connector's 5V rail.
The process of prepping for CircuitPython is pretty painless, as the device comes with a bootloader preinstalled which presents internal flash as a ~8MB drive visible to Windows. From there,
installing the MiniPython interpreter image is literally drag & drop; whereupon the thing automatically reboots and comes back up as a CircuitPy. With a whopping 48KB left available for the user's scripts.
Now looking into how to add the SPI CF reader boards I bought... amusingly, they're twice as big as the processor.
But hey, they too were cheap. Even with the Amazon next-day premium, ~$30 Canadian Pesos for 3 of each. I think that's damned reasonable for what these little bit-munchers offer.
mnem