If we really want to support local restaurants (and give them better chances of post-COVID survival), we should do exactly as stated above: call in to order directly.
Do not give GrubHub, Uber Eats, and similar services a large portion of your order total just for being an easy-to-use middleman. The vast majority of restaurants around today are capable of processing payments and handling pickup/delivery themselves.
While these restaurants fight to stay alive in unprecedented times, the least we can do is put in a bit more effort for an order of food we would have placed and paid for anyway.