I was led to this work because of the fomu [1]. Also, if you're familiar with the Precursor [2] you'll realize the second, smaller fpga inside is the iCE40 as well (which makes sense, the same people responsible for tomu/fomu are involved with the precursor).

[1] https://tomu.im/fomu.html

[2] https://www.crowdsupply.com/sutajio-kosagi/precursor