Need to distinguish the 3 usages of Blinka

[dglaude]

Current Blinka introduction is limited to SBC

Blinka brings CircuitPython APIs and, therefore, CircuitPython libraries to single board computers (SBCs). It is a pip installable Python library that runs in normal "desktop" Python. The CircuitPython runtime isn't used. CircuitPython libraries can also be installed via pip. See the guide for further details.

In reality there are three different use case:

1. Blinka for SBC (as above)
2. Blinka for MicroPython (mostly RP2040 with guide: https://learn.adafruit.com/circuitpython-libraries-on-micropython-using-the-raspberry-pi-pico that apply to Pico but also Feather RP2040, ItsyBitsy RP2040, MacroPad RP2040, Trinkey QT2040, QT Py RP2040)
3. Blinka for Python on a computer (Win/Linux/Mac) by adding GPIO with 3 differents guide:

• For Pico https://learn.adafruit.com/circuitpython-libraries-on-any-computer-with-raspberry-pi-pico
• For MCP 2221 https://circuitpython.org/blinka/mcp2221/
• For FT232H https://circuitpython.org/blinka/ft232h/

Having a better way to describe those, but also filter the list of board for only SBC, only "RP2040" or that latter use case could help.

(some improvement can also be done on the learn guide side to help with this, or better linking to existing guide)