Blinka is our CircuitPython compatibility layer. It was originally written as a compatibility layer to run on top of MicroPython to work on boards such as the PyBoard and allow libraries written for CircuitPython to work. This allowed more library re-use and fewer libraries that needed to be maintained.
Blinka was soon adapted to work on Linux-based Single Board Computers to allow those same libraries to work on boards such as the Linux-based Raspberry Pi computers (not to be confused with the Raspberry Pi Pico microcontrollers). It gained a lot of popularity there was expanded to run on many more boards. It wasn't used much on MicroPython at that point and there weren't many guides that showed how to run Blinka over MicroPython.
When we recently tried to run Blinka over MicroPython, there were a few things that needed to be fixed up to get it working. While we were at it, we decided to add support for the Raspberry Pi Pico when running MicroPython.
There's already another way to run Blinka on the Raspberry Pi Pico using the U2IF firmware, but the difference is that Blinka is running on the host computer and the Raspberry Pi Pico is acting as a passthrough. If you're interested in running it that way, be sure to check out our CircuitPython Libraries on any Computer with Raspberry Pi Pico guide.
Additionally, you can always run CircuitPython natively on Raspberry Pi Pico. However, if you would like to run Blinka on a Raspberry Pi Pico or any other supported board running MicroPython, then this is the guide for you.