Geese being flock animals.. he would not be happy long term without one of his own kind. If you are able to give a friend.. that is the humane thing to do. Even another male COULD work. When introducing animals, there always seems to be some challenge... look into the proper was to introduce geese friends.. for chickens, it's a look but don't touch set up for a short while.. but I am unfamiliar with goose behavior.
Sorry for your loss.
Older female is better than older male in my experience.. but I've also had it be fine both ways!
He needs a friend, geese just don’t do well alone, any goose male or female will do, sometimes even females will start squabbles with males when they’re newly introduced but they’ll be happy with each other once they get used to each other.