I never said, Boruto isn´t canon. I was only wondering where 8 Gate Lee is coming from, when it not happend in Naruto, or Boruto. It is a character which isn´t canon, since Lee has never displayed the feats (Unless i forget something) Using feats from games, and other media in the other hand counts as non-canon and would be more "composite Lee".
No. Never stated, never shown. At least not from my last state of knowledge about Naruto.
That is more based on assessments, since Lee should able to use Guy his repertoir of abilities. Proof for that is non-existent, not even in the Databooks.