What I read is that God hardened Pharaohs heart not how. I make assumptions as well. GOD told Pharaoh to let His people go and the rest was how Pharaoh reacted to Gods commands. Like those in Rev who cursed God as God poured out punishments they refused to admit guilt and repent. Even though God had their lives in His hands. THEIR hearts were hard from sin. I don't think we are far apart.When I read the things you wrote, it tells me you really don't understand the narrative or you wouldn't have to reach so far out of the text to make your point.
Clearly, Pharaoh hardened his own heart. The text is explicitly clear on this. The text is also explicitly clear that God hardened Pharaohs heart.
Within the narrative, the hardenining starts with Pharaoh hardening his own heart, to God hardening Pharaohs heart.
Perhaps it's worth noting who Pharaoh was, and what he represented.
What is it about the text in regard to God hardening Pharaohs heart that rubs you the wrong way?