“M3GAN 2.0” might not have been a box office success, but it was the first horror movie many viewers turned to as the Halloween season begun this year. According to a special Hallowee n report from Nielsen summarizing horror movie viewership each October since 2021, the “M3GAN” sequel was the most-watched horror film on TV during the week of Oct. 1-7, with a total of 115 million viewing minutes on Peacock. (Data for the rest of this month is not yet available.) That statistic was counted across