Here in the western US we have em too. Diesel bowsers have a second blue hose attached. You put one in the fuel port, one in the def port, and then let them both fill up

I think I've seen those pumps here in Germany as well, and I'm pretty sure you can get AdBlue in canisters (I have one in the basement that I forgot putting back into a rental).

Yes, this (plus that the whole thing is more convenient than filling up the washer fluid) makes the whole "we don't want the customer to fill it up" even more absurd.