What should I do if I live somewhere where fucked up event happens now? Or what kid in Belgorod/Odessa should do?

Suffer. Studies like these are American/European centric in the first place. Their sample size never includes other countries (not because the researchers are evil lmao, but because they want to isolate this "phone factor"). A kid in Odessa is most likely suffering from the war today rather than suffering from the effects of Instagram.