Yes.
Real soy sauce is made from the soy bean which is considered kitniyot. If you were able to find a kosher l'Pesach brand, it's not allowed for Ashkenazim. There are several brands of imitation soy sauce for Pesach.
I was told that soy contained wheat, and wheat has to be unleavened for Passover.
It has to be labeled as kosher for Passover with reliable supervision. If it has such a labeling, it may be used only by non-Ashkenazim (Sephardim, Mizrahi). It does contain soy, but has no gluten.
Yes, soy lecithin is generally considered kosher for Passover as it is derived from soybeans and not chametz (leavened grains). However, it is always recommended to check for specific kosher for Passover certification on the product packaging to ensure compliance with Passover dietary guidelines.
I don't think so!
Real teriyaki sauce, which contains soy sauce, would be kitniyot. There are imitation teriyaki sauces available for Passover.
There are a number of companies that make kosher l'Pesach imitation soy sauce. As soy beans are considered kitniyot, imitation soy sauce emulates the taste of the real thing but does not contain any soy.
You can try lactose free milk or soy milk.
There are soy based substitutes for dairy products, such as soy milk and soy ice cream. If you are interested in soy milk, allow me to recommend the Silk brand; that is the tastiest.
You can buy meat substitutes made of soy, such as soy dogs, soy sausage, soy "bacon", soy jerky, etc.
Soy como soy was created in 1998.
No. Soy or soya are considered nouns for the plant and its extracts. It is used as an adjunct in terms such as soy sauce, soy flour, and soy milk.