I mean I own a few. But they don’t look like Luffy’s.

I haven't, but imma buy one for working on my garden and it will not look like one, sadly.

I have multiple straw hats, but I have never seen one piece.

In the sense that chronologically I saw one piece before I purchased a straw hat, then technically yes I suppose.

I'm not about to draw a correlation between an anime I first caught a few episodes of on cartoon network in 20 or so years ago and the Panama hat I purchased a decade later though.