PC: Polynesian-Mapuche alliance resists Spanish colonization

[Acausality]

While migrating to New Zealand in the early 1300s, a significant Polynesian settler population (with animals) is blown south by a freak storm and gets caught in the powerful eastward winds of the roaring forties. They are carried to the Chilean coast of south America. Either unable or unwilling to sail back to familiar lands (a risky proposition without knowledge of islands), and considering Chile an acceptable alternative to New Zealand, the Polynesians settle down and begin cultural and technological exchange with the local Mapuche.

There's suggestive evidence that Easter Islanders visited South America and the Mapuche specifically, with one presumed contact event happening as late as 1370 (involving south american genetic material moving to easter island, though contact was almost definitely Polynesian-initiated). Let's take this at face value and roll with it.

When the Easter Islanders show up around 1370, they recognize the language and culture of the local polynesians, who serve as interpreters and intermediaries with the native americans. Whereas in OTL the islanders linger briefly and then return west (perhaps taking some locals with them), here they begin to travel between Polynesia and the South American coast, encouraging further polynesian migration when living conditions on Easter Island worsen. They explore more of the South American coast, perhaps contacting the Inca Empire before it begins violently expanding into Mapuche lands and finding some mutually beneficial form of trade or technological exchange.

In the early 1500s the Spanish arrive, though their focus is initially on Peru/Mexico compared to Chile. There's still likely to be a big outbreak of epidemics, and the Spanish still have the tech advantage, but in OTL all that happened and the Mapuche still managed to resist colonization to an impressive extent, even destroying many Spanish cities. In this ATL, I imagine the more populous region does even better, right?

I guess my main questions are:

1. How useful would the Polynesian package be for the Mapuche in general? I imagine pigs and chickens are pretty useful generalists to have around, and the Mapuche were willing to adopt new animals from the Spaniards, but a lot of crops are meant for latitudes closer to the equator and might not be as useful?
2. How useful would travel up and down the American coast be? South America had a pretty wide variety of civilizations throughout the 15th century: is there anything meaningful to gain from contact with the Incas and Aztecs, either for the Mapuche-Polynesians or those other civilizations? Tropical crops, at least, seem like they'd be desired by the Incas and Aztecs.
3. Does ongoing contact with South America change anything for the pacific polynesians?
4. Are there any plausible butterflies that further delay Spanish colonization? I thought of Magellan getting sidetracked by Polynesian tales of New Zealand, sailing too far west, and his expedition dying of scurvy, given how poorly organized his pacific crossing was in the first place, but I'm not sure how plausible that'd be in practice.
5. Does all this combined allow for a South American group to resist Spanish colonization to the point of functional independence (as opposed to the weird intermittent war that the Mapuche had going on in OTL). If that's not on the table, can we see a Maori situation where the locals retain high cultural significance?

 

[Arkenfolm]

Why would the Polynesians be allies with the Mapuche? If they migrate to South America, then they are just as much intruders as the Inca or Spanish. Although even if half of Rapanui up and leaves, that would still be a small enough number the Mapuche could just assimilate them if there's already community links.

Assuming they even reach the Mapuche and not another coastal group in northern Chile. Easter Island is fairly north and the currents and winds move ships further north.

1. Not really for the Mapuche, beside pigs/chickens (if we assume they reach Rapanui). But for those further north, coconuts, breadfruit, etc. would be useful.
2. It certainly was OTL given the exchange of chickens and sweet potatoes/kumara. For the Polynesians, just having regular contact gives a reason to keep sailing, since IIRC one theory is they hit a "dead end" that made long distance voyages rarer and rarer since there were no unique resources at the opposite end.

The other big one is sailing technology. Coastal South America had decent sailors (they did occasionally reach as far as Mexico) but if they incorporated Polynesian techniques and ship design then they'd definitely kickstart the regional economy. Even more marginal groups like the Chonos would benefit .
3. See above. The Polynesians on one end would be wealthier (especially if they get Inca silver) which would filter its way back through the Pacific. But even other goods (like, say, tanned hides) could be valuable simply because they'd be exotic.
4. Avoid Spanish conquest of Mexico and the Inca. Then their empire will be much more limited and focused on dealing with the remnant Aztec/Inca state or conquering random Maya states.
5. Probably not, even if the Inca survive. Spain has every reason to "encircle" the Inca, if only as a base for future conquistadors or peaceful merchants. And the Mapuche/other Chilean natives wouldn't really be strengthened in the areas that count. Worse, they have silver too, so they'd be lucrative for conquistadors and potentially greater in number so would be fed into silver mines. They'd still form the base of a substantial mestizo population. At best they'd be as important as the Nahuas were to Mexico or Quechua to Peru, while the Mapuche themselves hold out further south like OTL.

The Rapanui would fare just as bad as OTL. Spain would notice their trade, notice they have silver, and subdue their homeland. Many would be forcibly brought to the mainland and the remaining population would suffer heavily. Much like OTL, or see the fate of the Chamorro for another island group the Spanish decimated.