alternatehistory.com

https://en.wikipedia.org/wiki/Holy_Roman_Empire#High_Middle_Ages
In 955, Otto won a decisive victory over the Magyars in the Battle of Lechfeld.[34]:707 In 951, Otto came to the aid of Adelaide, the widowed queen of Italy, defeating her enemies, marrying her, and taking control over Italy.[35]:214–15 In 962, Otto was crowned Emperor by Pope John XII,[34]:707 thus intertwining the affairs of the German kingdom with those of Italy and the Papacy. Otto's coronation as Emperor marked the German kings as successors to the Empire of Charlemagne, which through the concept of translatio imperii, also made them consider themselves as successors to Ancient Rome. Additionally, in 963, Otto deposed the current pope John XII and chose Pope Leo VIII as the new pope (although John XII and Leo VIII both claimed the papacy until 964, when John XII died).
This also renewed the conflict with the Eastern Emperor in Constantinople, especially after Otto's son Otto II (r. 967–83) adopted the designation imperator Romanorum. Still, Otto formed marital ties with the east when he married the Byzantine princess Theophanu.[34]:708
Their son, Otto III, came to the throne only three years old, and was subjected to a power struggle and series of regencies until his age of majority in 994. Up to that time, he had remained in Germany, while a deposed Duke, Crescentius II, ruled over Rome and part of Italy, ostensibly in his stead.
In 996 Otto III appointed his cousin Gregory V, the first German Pope.[37] A foreign pope and foreign papal officers were seen with suspicion by Roman nobles, who were led by Crescentius II to revolt. Otto III's former mentor Antipope John XVI briefly held Rome, until the Holy Roman Emperor seized the city.[38]
Otto died young in 1002, and was succeeded by his cousin Henry II, who focused on Germany.[35]:215–17
Henry II died in 1024, and Conrad II, first of the Salian Dynasty, was elected king only after some debate among dukes and nobles. This group eventually developed into the college of Electors.
It would seem that the founding of the HRE goes right back to Otto the Great and his marriage into Italy, which opened the path to imperial coronation and marriage into the great Empire of the East and legitimacy with the Catholic Church.

So assuming Otto doesn't marry Adelaide due to Lother living and Otto goes on to focus on his German holdings and perhaps further push Eastward and secure Bohemia and parts of Poland.
https://en.wikipedia.org/wiki/Kingdom_of_Germany

Would the Ottonian dynasty then become the hereditary monarchy of a Kingdom of Germany or was there some other means of transfer of power at the time? It would seem that Otto I had pretty much created a centralized kingdom before forming the HRE:
https://en.wikipedia.org/wiki/Ottonian_dynasty
Otto I inherited the Duchy of Saxony upon the death of his father in 936. He continued his father's work of unifying all of the German tribes into a single kingdom, greatly expanding the powers of the king at the expense of the aristocracy. Through strategic marriages and personal appointments, Otto installed members of his own family to the Kingdom's most important duchies. This reduced the various Dukes, who had previously been co-equals with the king, into royal subjects under the king's authority. Otto also transformed the Church in Germany into a major royal power base to which he donated charity and for the creation of which his family was responsible. After putting down a brief civil war, Otto defeated the Magyars in 955, ending the Hungarian invasions of Europe and as well as securing his hold over his kingdom. The victory against the pagan Magyars earned Otto the reputation as the savior of Christendom.

Then the problems started:
By 961, Otto had conquered the Kingdom of Italy, which was a troublesome inheritance that none wanted, and extended the Kingdom's borders to the north, east, and south. In control of much of central and southern Europe, the patronage of Otto and his immediate successors caused a limited cultural renaissance of the arts and architecture.
Though at the time the conquest of Italy was probably financially and culturally beneficial for the realm, politically it would create a mess that would ultimately malform the HRE and cause it to limp on. Without Italy as an albatross around the neck of the Ottonian and Salians and several other dynasties going forward it would seem to me that Italy would be its own kingdom sooner or later, France forms into its own, and Germany was already a kingdom. So is this the best POD to get a united Germany early on?
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