Sadly, this is also what remdesivir does, although its an infusion. Also, the evolutionary pressure from vaccine-induced or natural antibodies also encourage mutations. The gamble is always complexity-related - will a random change help or hurt more.

People have also suggested a mixture of the Pfizer and Merck oral meds in order to reduce the chance of (quickly?) developing resistance to the protease. Similar to how HIV cocktails are used.