I’m from the UK and my partner is from the States. Every year she has the kids leave milk and cookies out for Santa, which I find odd because we left out sherry and a mince pie in my house. At the same time, we live in Scandinavia and I’m sure the Christmas gnome (julenissen) is unhappy about the lack of porridge.
Slovakia: nothing.
When I was very young kid I have proposed to leave something for him but my family talked me out of it.