I've recently been studying the incredibly likely occurrence of Polynesians visiting South America, and probably Southern California as well between 1500 and 800 years ago.
In OTL all this did was send the sweet potato to several Western Polynesian islands (the sweet potato's in the Eastern Polynesians appear to have come from the Spanish the other way), gave Peru the chicken, and a Polynesian style boat and fishhooks to California, along with a couple of loan words.
Now is it possible for some sort of consistent,long term trading to come about? It appears that historically there were only occasional visits between the Polynesians and America, and nothing that could be reliably counted upon.
Could the Incans, Chavins, Moche, etc, have traded copper, guinea pigs, cotton clothing, gold, silver and many other things, and in return gotten new types of bark cloth (it was a main trade item to Europeans from Hawaii in the 19th century), Sago, pigs, pearls, exotic feathers, and spices?
Or was it simply too far away to reliably get back and forth?