Could you please tell me if nutritional yeast powder is approved for SIBO group? I would like to use about 1 Tbsp in my shake.

As long as you feel good on it and don't bloat, it should be fine. Nutritional yeast is non-viable (won't grow) and supplies nascent B vitamins and RNA/DNA factors. If you get gassy, then it would not be suitable at this time. But if you tolerate it well, then terrific.