I had my lineage proven to Charlemagne in August 2019 & was able to become a life member of the Order of the Crown of Charlemagne in the USA using the first proven and now accepted Royal Spanish Gateway Ancestor Juan Montes Vigil who connects to Charlemagne through the Ponce de Leon family. The line goes from Taos, New Mexico to Mexico then over to Spain, Italy and then France. The people in between are very Notable and are Founders of Modern France, Italy, Spain & Portugal.
The best advise I can give is never trust online trees that have unverified sources, use only period documents, and try to only use Birth, Marriage, Death, Wills & land records. That is how my Membership was proven.
I am in the process of entering my OCC Record Copy lineage that was approved, but I need to be Pre-1500 approved to do it here. I still need to add 5 more Generations to my tree to connect to other Wikitree profiles that go up.
It is Very Easy to say you are a descendant of Charlemagne, buy Very Hard to prove it using modern Genealogical Standards.
https://www.charlemagne.org/krslwksh.html