It always trips me up how ij is one letter in Dutch since I learned Dutch spelling with ij and not the y version. The y version was the normal Greek one.
For non-Dutchies: y = y and y = ij, they both have different sounds.
For non-Dutchies: y = y and y = ij, they both have different sounds.
See also: https://en.wikipedia.org/wiki/IJ_(digraph) and https://nl.wikipedia.org/wiki/IJ_(digraaf).
And that codepoint was actually massively helpful to represent the ij-as-single-letter in the practice application: https://lingo.vincenttunru.com
It's really a digraph, a phoneme made out of two characters. But it's an inconsistent digraph in that both characters are capitalised together, whereas with other digraphs, only the first is capitalised.
It's not entirely true that 'y' is only used in foreign words. It's used in import words that have been part of the Dutch language for a very long time now. 'Royaal' and 'symbool' are not spelled like that in any neighbouring language, so they've been thoroughly Dutchified over the centuries. They're not foreign anymore.