Is it possible or allowed to create a Extension that will allow you to track who you what games you watch and which streamer and for how long ? I want to create an Extension that does such a thing but I don’t know if this is possible and I don’t know if Twitch will allow for such a thing.
No it’s not possible.
An extension is only on pages of one of more streamers.
So you’d only be able to track that streamer which basically means incomplete data.
And it’s not the point of extensions