Thank God Truman had the common sense to fire him.

Yeah, World War II can do that.

One of the very few good things the Qing dynasty (or any Chinese imperial dynasty for that matter) did.

The answer you are looking for is no. I am not a constitutional scholar by any means, but I am interested in the concept of constitutionalism.

There’s an unwritten constitution, which is still a constitution

I and most if not all constitutional scholars would politely disagree with that. In order for a constitution to be valid, it has to be written down in some form that way everyone can agree to some extent (there will still be some gray areas, like what is/isn’t a right for example) on how society should be governed. If there isn’t a constitution of some kind, it would just be no different than the absolute monarchies of old where they either claim some divine right to rule and do whatever they want or just go as far (like Louis XIV famously declared) to say that they are the state.

“Constitutional” monarchy my ass