Not sure about gluten. I seem to do OK with it but I'm not a big grain eater.
Soaking millet won't help anything as far as I know. It should be low cooked [about 210*F] and it doesn't cook well in a Thermos.
Maybe do like I sometimes do and slow cook oat groats or barley in a Thermos bottle overnight in a 2:1 boiling water/grain ratio.
I make rice sticks sometimes, which is a form of pasta. I'd say a little of it may be OK if you have it with plenty of vegetables or legumes. I wouldn't make a meal of it in itself.