Is Halloween even a thing outside the US?
Oh yes. Well, trying to be.
It's mainly pushed by corporate business in the retail sector, as an excuse to sell more useless tat to the public.
Actually, it might be like that within the US too, for all I know.
I mean it's a "thing" here too in that some shops will put up decorations on the display. That's about it. Kids don't trick-or-treat, and it sure as shit doesn't mean anything to anyone.
It kinda doesn't mean much to anyone anywhere. The festivities around Halloween have long since overtaken the significance behind them. It's not Dia de Muertos, wherein the festivities are there as part of remembrances for deceased loved ones. It's an excuse to dress up (or let the kids dress up), go out, and have fun.