I remember George saying something about C-3PO like ‘he begins as a droid, he ends as a droid…he has a sad droid life in between’ I can’t find the exact quote though.
My impression is that he genuinely doesn’t think that the droids are sentient, and my theory that they gain sentience and true personhood with the passage of time is me giving the movies too much credit.
I won’t change my theory, though.