The more I read, there were many similarities between Hitler, who was similar to an emperor, and the Holy Roman Emperors. He also had a sense of history and part of his drive for living space was to create the next generation of the Holy Roman Empire. He had a relationship with the Pope, they had the Concordat, and even though they weren't on the best terms, they co-existed (Holy Roman Emperors also clashed with various Popes). It was about maintaining order, and defeating atheist Communism and Soviet nihilism.
Take a look at the standards the Nazis carried...very Romanesque...(Gold eagle etc etc) I believe he also copied the Roman Modus Operandi when it came to invasion or rather occupying invaded countries.
There seems to be some confusion here. The HRE was primarily Germanic and I haven't seen any symbols that the Nazis carried forward. The Roman Empire was primarily Italian in origin (although it later split into East led from Constantinople and West led from Rome). This Empire contained many of the symbols and trappings that found their resurgence in Nazi Germany.
Hitler also copied Napoleon (Europe conquest, eagles, invasion of Russia, Imperial Guard, police state with files for eveybody etc...) . Btw the HRE also comprised part of Italy, all the way to Rome.
The HRE also had parts of Poland and Czechoslovakia, with Prague at one time being the capital of the HRE, which is why Hitler wanted Czechoslovakia and motivation for Western Poland besides Danzig,
https://en.wikipedia.org/wiki/Holy_Roman_Empire The Nazis may have dreamed of this: https://en.wikipedia.org/wiki/Holy_Roman_Empire#/media/File:Holy_Roman_Empire_ca.1600.svg but they ended up with this: https://upload.wikimedia.org/wikipedia/commons/thumb/8/80/Map-Germany-1947.svg/220px-Map-Germany-1947.svg.png
The Holy Roman Empire: 'Neither holy, nor Roman, nor much of an empire.' (To roughly paraphrase Voltaire.) The HRE does not match the sort of setup Adolf had in mind. If anything, federations like that, and the later mess that became 'Germany' were quite probably the opposite of what he wanted to build. Part of the historical motivation and justification for the belief that only a strong, centrally controlled dictatorship of genuinely subservient or totally occupied states would do for the Third Reich.
I do have sources. I've read different articles and papers on the subject. Off-hand I can't remember so I'll re-research it and post.
If anything, Hitler pinched the idea for the SS from Plato's Republic- a state-sponsored army which was only allowed to breed/intermarry amongst the "right" people, ie their own kind. Book IV- http://www.iep.utm.edu/republic/
I'll post 2 articles. There are more. Some may not consider these reliable, or more of opinion, but it at least starts the conversation and gets ideas flowing. https://www.thetrumpet.com/literature/read/1194.6.0.4/hitler-and-the-holy-roman-empire?preview/hitler-and-the-holy-roman-empire http://www.iiipublishing.com/blog/2013/11/blog_11_19_2013.html
I'm not sure of either sources. Both seem to be blog pieces with a religious bent. I would like to see more objective pieces. Neither of these are sourced. Anyone is free to say what they want, but without citation, it's just opinion. I would hope for more scholarly material.
That's why I said these may not be considered serious, but they start the conversation and give some insight.