Like Thanatos said, it's experimental. There is a guy in Australia(correct me if I'm wrong, somebody probably has the link) that has a process pretty well down for GF all-grain. All the grains you describe could be used for GF AG brewing, the problem is getting them malted consistently. From my own malting experiments, quinoa is very easy to malt. Sorghum isn't tough either. My two attempts with millet got moldy before they modified, YMMV. There are also a couple of oat malts, Fawcett Oat Malt and Simpson Golden Naked Oats, that some people use and have success with.