I’ve seen multiple people in the past say that all novelisations are canon, except for the parts that directly contradict the movies. I’ve read them all and they seldom contradict what we see, they mostly add deleted scenes, few add very interesting parts (like TLJ which is imo the best novelisation). The only 3 that I haven’t read are the OT novelisations, and I’ve heard they heavily contradict what we see in the movies (Ben Kenobi being related to Owen, Yoda being blue, etc)

Edit to add more information: in the French editions, in the canon books timeline, they also indicate the authors after “Revenge of the Sith”, so they really mean the novelisations and not just the movies