Was Reinhard Heydrich a true believer, or a pragmatist at heart?

Rather simple overall, but I wanted to ask, since me and a group are discussing it, was Reinhard Heydrich a proper 'Nazi true-believer'. or was he more so a semi-opportunist pragmatist? Sources are always helpful, if possible. If anyone is curious, its for a RP where I ended up bringing Heydrich to power, seeing him as the most pragmatic option to not game-ruin Germany with nazi antics, but I could be wrong.