Japan has 勤労感謝の日 which is typically translated as "labor thanksgiving day" in English and is 23 November this year. We have no national public holiday on May 1st this year. I think it's possible for some of the Golden Week holidays to fall on the 1st technically, but I'm not 100% sure on that.
According to https://www.norden.org/en/info-norden/public-holidays-greenland
May 1st in both International Workers Day and Anniversary of introduction of home rule. These are not public holidays, but provide time off under collective bargaining agreements.
So Greenland should be striped Red, Green, Gray and one more color.
The map certainly isnt perfect. Austria for example should be yellow since we official just celebrate an ominous "state holiday" and nothing else. Which essentially was just a compromise in order to not anger the bourgeoisie back when it was made a holiday.