@Harm42
Thanks a lot, your solution worked on my S2 watch + iPhone 6S with iOS 14.0.1.
Worth mentioning the 2.4 ghz network + network reset made all the difference, I had tried this method before with a 5ghz network and nothing changed, so do try that if you're having this problem. I was almost giving up after hours trying solutions to update, couldn't even believe it when I saw it finally downloading...