They're planning a Six of Crows spinoff which is based on the author's Crows duology (these are the books Kaz's gang are actually from) and while still YA, avoids a lot of the annoying tropes you see in the genre and is - in most people's opinion - far better than the main trilogy the show is adapting. You even see it teased at the end of S2 when Kaz mentions >!a drug that enhances Grisha abilities!<.

Pretty sure the main reason the Crows are even in the show (since their duology isn't set until after the events of the trilogy) is because they're much better characters from a more praised set of books - IIRC the showrunner even said he wouldn't make the show unless they could be in it.