Don't know about smokey soy sauce, but depending on the dish, you could add a bit of chipotle (chipotle powder, chipotle hot sauce, or whole chipotles in adobo) or smoked paprika for a touch of smokiness.
Bragg's is an all natural soybean based sauce that has what might be described as a slightly smoky flavour. I used it in my special diets cooking at camp for celiacs and vegetarians. The vegetarians loved tofu marinated in it and fried. They said it tasted almost like it was bbq'd.
Hope that helps.
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