It also goes by the names alnus viridis, green alder, dune pepper (or Poivre des dunes in French).
It is milder than pepper, with a bit of a coniferous resin taste. It looks a lot like long pepper but tastes very different.
It’s technically not a pepper, but the catkins from a variety of alnus brush.
I have no clue where you would find that in Europe and the places I know around here don’t seem to ship overseas.