Very happy to see this.
However: given authentication is one of the most important pieces of the interaction with twitch, one of those that gets a lot of questions, and the thing that you need to make sure you get right, I am of the opinion that leaving it out is a large disservice.
I understand if its not in immediately, but I am in favor of this bloat if it means that I can mock the full auth process without having to hit twitch’s production servers (as I do now).
Mind, having the ability to disable it (just checking, but not validating tokens etc) would be ideal if that is not the component being worked on