I think if I were to regard these things as canon is a fool's errand, much like the fool's hope of the quest succeeding. The films were great but hardly canonical, and often left out some of the more excellent elements in the favor of pacing or dramatic tension, as one of my good friends would complain as we watched it. That was OK though because we thoroughly enjoyed the ride.
Adaptation is something that lining up with "canon" will lead to more frustration than enjoyment, which is not the way I want to participate in entertainment. Tolkien wrote the Hobbit and Lord of the Rings because there were no stories out there that he enjoyed reading. So, he decided to write his own, based upon his great love of language, history, and England. That I can still derive a measure of enjoyment from a work he wrote to satisfy his own need is remarkable in of itself.
That Rings of Power is not canonical takes about as much away from my enjoyment of the show as the Lord of the Rings film was diminished by the lack of Glorfindel, Prince of Dol Amroth, more assertive Gandalf vs. the Mouth of Sauron, etc.
Where's the line?