I looked up with Google USA to see Soyless Soy Sauce products available on the market.
It did not hit.
I retyped and said "Non-Soy Soy Sauce."
It could not give me the product. At least not on the first several pages.
Hurray, I know better than Google (USA)!!!!!!
Yes, there IS a product available within USA which does not use soy to make soy sauce.
It is called "Soramame Soy Sauce" meaning "Broad Bean Soy Sauce" and its ingredients are only broad beans and salt. And frankly, nobody can tell the difference between soy sauce and broad beans sauce.
Sadly, it is not even on my beloved Amazon.com.
I wish I could give you a link to this product, but there is no English website who talks about Soramame Soy Sauce. It is made by small Japanese company called Takahashi Shoten in Kagawa, Japan.
They deliver within Japan, but not to USA.
I've seen Soramame Soy Sauce in Nijiya Market and Mitsuwa Marketplace.
So if you live near by these Japanese supermarkets, please go visit them!
Remember, Soramame Soy Sauce does not occupy big part of the shelf,
so it's a good idea to call first to reserve your bottle.
But if these supermarkets are not in your area, there is one more thing you can try.
Contact your Asian food market, preferably Japanese, and ask if their importer or distributor have access to this soyless soy sauce. It tastes totally worth it to give it a shot.