All of western Europe has really well developed pilgrim trails. I hiked the coastal one in Portugal a few years ago that leads into the main Spanish ones.
As I understand it, the Nordic pilgrim trails aren't anywhere near as well developed as ones closer to Camino de Santiago.
The St. Olav's Ways trails were only (re)established in the 1990s, and as I understand it, only a couple thousand people do it each year. (My sister and I were talking about doing it this last summer, but plans didn't work out.)
I think this is true, apologies if I oversold them a bit. The Portuguese one I did was also being built so we had to take detours at time. Sometimes it was unclear, but at the same time there were posters next to the road on how it was going to look soon.