For a gluten-free soy sauce alternative, consider using a gluten-free tamari, which is easy to find.
Not all oats and grains are gluten-free and some may be processed on equipment that also processes gluten, which means they can carry up to 10 percent gluten content without legally including wheat or gluten as an ingredient on the label. Gluten-free-labeled items must contain less than 20 parts per million of testable gluten, so extreme care should be taken when sourcing these ingredients if celiac disease or extreme gluten sensitivity is a concern.