Can gluten-free flour be cooked and eaten as a hot breakfast cereal?
Yes, you can do it. It will taste more like a pudding (not necessarily wheat pudding) than like a cereal. The consistency will depend on the grind size, and can get down to standard starch pudding, or be a bit gritty like semolina pudding. 

Most people won't find the taste of a pure flour + water or even flour + milk pudding interesting enough, so you can experiment adding stuff to it. You're only limited by your own imagination.