Mash the goat cheese, pepitas and 2 to 3 teaspoons hot sauce in a bowl with a fork until combined. Spread the mixture evenly on 4 slices of bread, then top with the ham and avocado.
Toss the arugula with the olive oil, a few dashes of hot sauce, and salt and pepper to taste in a bowl. Add the arugula to the sandwiches and cover with the remaining bread. Serve with potato salad.