The Holy Roman Empire was a unified nation-state with a strong absolute monarchy.?

Far from it... the HRE was not at all unified and was more of a confederation of lesser kingdoms, duchies, principalities, bishoprics, free cities, and many other kinds of jurisdictions whose heads of state voted on who became emperor. He was also not an absolute monarch. He ruled with the consent and support of the lesser heads of state. He was the absolute monarch in his personal domains in Austria however.