It looks like a Hungarian keyboard does not have a key for the dz ligature. So do they use that unicode codepoint in practice? Or is it just a ‘d’ followed by a ‘z’?

I see that DuoLingo has a Hungarian offering, but I would not touch it with a ten foot Pole.

Both Serbo-Croatian and Hungarian have these multi-character letters, but these Unicode points were created for the typographical needs (or rather, bad habits) of Serbo-Croatian. The "Dz" was probably included for the use-case where someone transcribes something in Macedonian.

One example can be seen on the Croatian 2kn coin, which features a tuna and a title written T U NJ.

Hungarian has more of these multi-symbol letters (with each letter having 1-3 symbols. It also has some other complications, such as having two "sz" in a row appear like "ssz", unless separated by a line break or a hyphen (then it's just two "sz").

IMO it was probably a mistake to let the article focus so much on Hungarian, as these Unicode points don't seem to be created for the purposes of the Hungarian language.

I miss 7-bit ASCII.