circuitpython-org/_board/feather_m0_supersized.md

layout	board_id	title	name	manufacturer	board_url	board_image
download	feather_m0_supersized	Feather M0 Supersized Download	Feather M0 Supersized	Dave Astels		/assets/images/boards/feather_m0_supersized.jpg

This is a [Feather M0 Express]({{ "/board/feather_m0_express/" | relative_url }}) that has been supersized by Dave Astels to fit a larger SPI flash chip than the default 2MB chip. It is not available for purchase.

It was documented as a DIY project here.