Since you are asking this on Travel SE I assume you also would want to visit such an island. I think I have found exactly what you are looking for, with the only downside, that it is not a Pacific island but in Europe:

Île du Levant

According to Wikipedia some 90% of the island is military and thus off-limits but the rest can easily be visited.

Being nude is allowed (and expected) everywhere on the public area of the island, except in the immediate vicinity of the harbour and on the village square. On these locations, it is formally necessary to wear what the French jokingly call French: le minimum, often a pareo or a string. In conformance with the relaxed atmosphere of the island, this rule is not really enforced, but generally well observed.

So I am sure you will be able to find there "native people who don't wear any clothes at all" even though I do have to admit that some of these people might not be natives but tourists like you.

Some more info can be found here and here [warning: some pictures there are NSFW] and on the French Wikivoyage.

When visiting you should stick to the etiquette (beyond clothing, or rather the absence of such) as indicated e.g. here

• Gawking is impolite. In fact, it's rude to stare, no matter where you are and no matter how the other person is dressed (or isn't). A nude beach isn't a peep show and if you're looking for a thrill, go somewhere else.
• Ask for people's consent before taking their photograph. This is also true no matter where you are, but especially if they're nude.

but also here. This is in line with what you cite that "they don't have any clothes ad were naked and that they do look into the eyes when they speak with each other and not on the breasts or ass etc."

I think the issue here is that anything that is easy to visit is less likely to have indigenous tribes or populations of any size that would not have started to wear clothes. Exceptions are the spring break populations in the USA etc.

So in order to answer your question, I would suggest you to take a look at a list that has all the most likely candidates, namely the un-contacted peoples of the world. What kind of clothes they wear is of course sometimes hard to say because, well they have not been contacted. But the chances that they wear Adidas sweatpants at least is very low.

All hunter/gather tribes that is uncontacted is usually naked at first. It's not until shortly after they done the loincloths. On the island of Yap (Micronesia) you may find some people in regular clothing but the clothing of choice is loincloths. Wrap around types that provide more coverage then the amazon style. Besides exposing a lot of thigh is considered indecent. But woman walk around topless and think nothing of it.