Here in Romania, it’s a pretty big deal. It’s a public holiday, so a lot of people have the day off. This year, for example, because it falls on a Thursday, the government decided to make 2 May a day off as well, creating a four-day weekend. Barbecues with family and friends are the national pastime on 1 May. Spending time outdoors in open spaces (“la iarbă verde” - literally “to the green grass”) such as woods, meadows, beaches, parks, etc., barbecuing and having picnics is also a staple. This year, I’m going with my girlfriend and her parents to Italy and Switzerland (Lake Como and Lugano) - which also means we’ll be voting for president abroad (4 May - first round of the presidential elections).


US doesn’t really celebrate it, but my city pretty much has protests every year.
Then again, we protest anything and everything, so it fits right in. :)
https://katu.com/news/local/portland-protests-vandalism-destruction-violence-businesses-protesting-may-day-pd-chief-bob-day-ted-wheeler-mayor-pro-palestine-palestinian-protesters-university-library-takeover-occupation-anti-war-israel-demonstrations
The next nationwide anti-Trump administration protests are scheduled for May Day.
Second this for the US. Nothing major as a nation, but various small things in different areas or cities.
I know Hawaii does a Lei Day- “May day is Lei Day in Hawaii”. Not a full on holiday, but there’s usually festivities of various levels around the islands.
The closest official thing in the US is Labor Day in September. Most people forget it is a workers rights day, though.
From Wikipedia: