Here's the coconut aminos on amazon. I guess it depends on where you live and what your options are, but amazon is pretty pricey for this stuff. I get it at my local grocery store for $6.99 and I think it's 7.99 at our Whole Foods. Still not cheap, but damn worth it. It's freaking delicious.
I don't know how this will work for skinless chicken, but I have done it with a cut-up whole fryer. Minced garlic, fresh squeezed juice from the fruit, with some grated rind nixed into Coconut Aminos
I marinate with that for several hours......the coconut aminos is a great product.
I got it from Stop and Shop. I’m not sure where else they sell it. Edit. They also sell it on amazon https://www.amazon.com/dp/B003XB5LMU/ref=cm_sw_r_cp_tai_3SBCCbVQT6N0Q
There is a soysauce alternative https://www.amazon.com/Coconut-Secret-Organic-Soy-Free-Seasoning/dp/B003XB5LMU?th=1
There are brands that make allergy free food, like Enjoy Life.
I don't know much about Japanese cooking, but this is a soy free soy sauce, but does contain coconut which isn't technically a nut. https://www.amazon.com/Coconut-Secret-Organic-Soy-Free-Seasoning/dp/B003XB5LMU
Also, I really like this site for desserts and snacks. http://petiteallergytreats.com/
Or Coconut Aminos which tastes like Soy, but only has 1g Carb per Tsp. http://www.amazon.com/Coconut-Secret-Organic-Vegan-Aminos/dp/B003XB5LMU