I do think that it was more than just a few small interactions, but I don’t think that they happened in Rapa Nui island, or that they got the chance to develop an Amerindian minority there. I think that, instead, the Polynesians had small coastal settlements here in South America, used for trade.

So those 10% admixture would be like in your other hypothesis - mixed kids raised Polynesian.

The key is that what you said is true for the Polynesians, but not for the Amerindians - from the Polynesians’ PoV the Amerindians were a big cluster of potential trading partners with exotic resources, but from the Amerindians’ PoV it was just a small island in the middle of nowhere, that could be only safely reached by knowing how to navigate the oceans - and at least Andean Amerindians likely didn’t know how to do it, as they were way more focused on land-based tech (terrace farming, road building, freeze-drying…).