"...So is 22nd of July 'Pi Approximation Day' in DD/MM countries then?"
I will be making a pie (Key Lime) for my family to celebrate today. I don't expect to get them to join me in singing a few rounds (which are, of course, the traditional music for Pi Day, similar to carols for Christmas).
My wife and daughter do not, in general, really get into the holiday spirit; Pi Day is more part of their nerdly husband/father's cultural heritage. But they'll eat the pie.
But a couple of years ago, my wife made some quite tasty quiches for 22/7. A quiche is, of course, "approximately" a pie.