Nope the gangstalkers, fema demons, and organic portals are coming from people they've offed and inserted a host once they've passed if they can get away with it, they then have a perfectly normal looking citizen that nobody knows passed on to use to Gangstalk People

They use these people for Gangstalking and the gangstalking always ends with A zombie like situation in which all the gangstalkers attack, they can then like flipping a switch turn them back into semi-normal looking citizens to gangstalk again

AS Far as I know I'm the only Survivor thus far