I've had fun using this website: https://www.cognomix.it/
You can type in a surname and see where in the country it's most common - or if it's one of those that are more widespread. :)

I suppose also it matters where one considers the North/South line.

Indeed! As a north European I don't want to intervene too much in that debate, I can just see that it seems to hold somewhat true still. And then there are the ones ending in -n, -l, -e etc. that seem to follow their own rules. ;)