To be fair, fillable PDF forms from public institutions still seem to be uncharted territory for large parts of Germany.
On the other hand: Why fill out PDF forms if you can just send HTML forms and submit them directly to the administration. This is how the Danish system works.
Or just use fax. That's how it works in Germany
But you can only fax during opening hours which are Tuesday 10:00 to 11:15
And during that time, you get an error report telling you the remote fax is out of paper (true story).