No. Soy nuts are whole soybeans, and roasting does not reliably destroy the proteins that drive soy allergy. Soy is a major allergen that must be declared on labels for exactly this reason, and a roasted, crunchy format carries the same risk as any other soy food.

Yes, and it surprises people, because whole soybeans and bean-based soy milk are not. The galacto-oligosaccharides that make soybeans ferment stay behind in the bean when the protein is extracted, which is why soy milk made from soy protein is low FODMAP at a full glass while whole bean soy milk is limited to a splash. The grade assumes a plain isolate: check flavoured products for added inulin or polyol sweeteners.

It depends on how it is made. Soy milk pressed from whole soybeans is high FODMAP because of its galacto-oligosaccharides (GOS), so it can cause bloating and gas. Soy milk made from soy protein isolate is low FODMAP and is the version most sensitive guts tolerate, so check the ingredient list.

Not necessarily, because the two foods fail on different criteria. Soy sauce is brewed and fermented and grades at the top of the histamine scale, which is what catches most people out. Edamame is unfermented and grades clean on histamine. What edamame does carry, and soy sauce carries less of, is the intact soy protein and the GOS. If you are soy allergic, both are off the table.

Traditional soy sauce is brewed from soybeans and wheat, so standard bottles contain gluten and are not safe on a celiac or gluten-free diet. Tamari made without wheat and labeled certified gluten-free is the reliable alternative.