A well-documented chorded keyboard project based on the Raspberry Pi Pico: the PICO Chord.
KBD.news Published April 17, 2022
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I'm not sure about the designer of this keyboard. The author of this write-up, introducing the Pico Chord, is Ben Everard (and there is no reference or indication of other authors). However, the owner of the Git repo and the demonstration video is Rob Miles.
The keyboard is based on the Cykey chord design by Cy Enfield which was used as the basis of the Microwriter and Microwriter AgendA devices developed by him and Chris Rainey in the '80s.
Here is a quick demonstration:
As Tim Rowledge points out in the comments, there is a more promising case design here – another project inspired by the Microwriter.