At the very least it happens in Flanders. I've seen ijs ("ice") capitalized in cursive as Ys[0] on an ice truck, for example.

Edit: from Wikipedia[1]: "It used to be common, in particular when writing in capitals, to write Y instead of IJ."

So it's an obsolete practice...

----

0. something along those lines: http://alphabetprintables.org/alphabet_printables_cursive/up...

1. https://en.wikipedia.org/wiki/IJ_%28digraph%29