I found this episode interesting from the perspective that so much human knowledge has been forgotten and rediscovered over the millennia. The production value of this series is a bit cheesy IMO, but the premise of this episode is of course plausible. Not only might we never know if the pre-Columbian Chinese or Scandinavian explorers spent significant time in N America, but in ancient world history there are likely entire civilizations with knowledge/technology that we don't know ever existed.

Well yea.... well maybe not actual Chinese but their ancestors came over on the Barent Sea land bridges. Made it all the way down to the tip of South America.

Stand-by for the CCP to expand its ancient claim over the entire SCS to now include ownership of North America, too.

Because there's no evidence for any of it?
The guy is simply a publicity hound who wants to sell books. This is the discussion on the map he is touting as proof of the Chinese arrival:

https://www.livescience.com/7002-map-fuels-debate-chinese-sail-world.html

And Zheng's voyage that he references is well documented and followed known trade routes. Spend five minutes looking at it online, and you will see there is zero evidence they circumnavigated anything,

But more to the point, when the Norse landed in Newfoundland a settlement was found with irrefutable evidence. A long wall isn't evidencing anything, though it's a fascinating mystery. One that mostly has a mundane explanation, like a boundary wall, or one to keep livestock in or out. But saying "hey China built the Great Wall and this is a long wall so...." isn't a valid argument. Show actual Chinese settlements. Or did they just turn around? If so, then why build a wall only to leave? Why don't native Americans have it in their folklore? Or in their dna?
And I say all of that completely ,acknowledging evidence could come later, But it requires real evidence, not largely discredited maps and fantasies about voyages that didn't happen.

/nerd history major rant.