Conspiracy/pseudohistory

https://www.reddit.com/r/AskHistorians/comments/911nhd/nazi_searches_for_supernatural_artifactspower/

/u/szdfan talks about that here and also mentions Otto Rahn, the closest thing to what you're asking about

https://www.reddit.com/r/AskHistorians/comments/6fj4w1/arthurian_legends_aside_were_there_any_historical/?st=jjxqdtui&sh=b1a731ed

/u/commiespaceinvader talks about the life and deeds of Otto Rahn