Another question. You call ET a fantasy, but call it science fiction in 6.
Those aren’t the same thing. Which is it?
Also, as far as your definition of movie about children, you maybe should define it more. It seems that there was only one ever made, which was ET.
You’ll need to cite other movies that qualify.
Were any even made that qualify under your idiosyncratic criteria in the 15-20 year window you ask about?
If so, what were they?
Science Fiction and Fantasy is the same thing for these purposes. Any significantly advanced technology is indistinguishable from magic. Children meaning pre- pubescent. Many Disney films qualify (Pinnochio, Bambi). E.T. sort of updated the Disney template for the post Walt age.