By area here are the 19 largest empires in history prior to 1450. How many of these were feudal?
Mongol
Abbasid
Umayyad
Yuan
Xiongnu
Eastern Han
Rashindun Caliphate
Golden Horde Caliphate
First Turkic Khaganate
Western Han
Achaemenid
Tang
Macedonian
Roman
Xin
Tibetan
Xianbei
Mali
Timurid
en.wikipedia.org
Here's another linked list of the 30 states determined to be "great medieval powers." How many of those were feudal?
en.wikipedia.org
There's no real broadly agreed on definition of feudalism, so it's hard to say (one reason historians tend to be moving away from that word). I'd argue that several of them definitely went through feudal phases (for instance the Han at the beginning and end of the dynasty, or the Achaemenids, whose nominally controlled satrapies often effectively operated as feudal fiefs). That said, of the first list, most of them would be "Clan" by CK2's standards, a few would be nomads, most would be settled empires ruling from cities, and precisely zero would be the sort of tribes represented by e.g. the Vikings in CK3.
As for the second list, it appears to be a random list of countries that someone has bothered to find someone using the term "great power" to describe in at least some context. My favorite footnote there is either that a source "uses the Vikings as an example of a great power that was not a Great Power" to justify having the Vikings in that list or "
“It became apparent that the German leadership in the West“ [after the year 1200]
“had ceased to exist and that the new French great power was rising in its place.”" to justify 1200 as an end-date for the HRE as a "great power" and then not bothering to actually add Capetian France as a great power (those are footnotes 2 and 9). I wouldn't use that list to make any reasonable statistical argument.
Given that we are talking about CK, I'd look at actual Medieval Europe, which saw the Vikings raid regularly, but outside the weak and fractured British Isles, didn't see them conquering significant territory (and did see them under regular military pressure from settled empires; no Norse leader would dream of conquering East Francia, but several Frankish and German leaders considered invasions of Denmark, and eventually coerced the Danish rulers to accept Christianity).