It looks like it was separately discovered by other people as well:
"but then someone published the 0day bug two days before our 90-day disclosure window was set to expire on April 25th. Oh well. Yes, this is the same bug that is exploited by fusée gelée, and that was just leaked by some other group (but we found it first)."
They also have a github page with enough instructions for those with a certain amount of technical knowledge to boot linux on a Switch.