Great topic! If I ever met my celebrity crush(es) (see: the Minogue sisters) in real life, I’d probably die. I’d be lucky to stammer out a request for an autograph.
Other than in the crowd at rock concerts, the nearest I have ever been to folks you might consider “celebrities” is at chess tournaments. I’ve stood feet away from American and world chess legends you’ve probably never heard of: Nakamura, Caruana, So.
Never talked to them at all though, as you are obviously prohibited from “table talking” during tournaments. However, I have chatted with, played against, and received instruction from lesser grandmasters.