It's also available as an in-person workshop [1], and I believe corporate trainings are a significant part of the Ardan Labs business model. They also do shorter versions of their workshops at Go conferences.

They're huge contributors to the Go community via their conference workshops, and I can't thank them enough for the knowledge that they've gathered, refined, and shared all these years. (I help organise GopherCon Singapore.)

[1] https://github.com/ardanlabs/gotraining