I was in it every year till the very end lol
Be the change you want to see. Reddit Secret Santa was always a pretty big logistical undertaking, it would take effort to make a Fediverse one.
Also Fediverse users might be less keen on the idea generally, as it involves personal information and addresses. A very cynical take is that harvesting this data was the real purpose of the Reddit SS, which can't really be ruled out.