To be honest, the Piedmontese sample on the G25 is from Val Borbera, in the far southeastern corner of Piedmont, and where I think they speak more Ligurian than Piedmontese (but I'm not sure about that). Thus, an area more similar to northern Ligurians and northwesterns Emilians than to Piedmontese in the Alps. While the Southern French on G25 is most likely a sample near the Spanish border.
The similarity between Italians and Greeks is due to various reasons, and it does not always mean that they have completely similar origins. The uniparental markers are only partly the same. As I know the thesis that modern Greeks, particularly continental Greeks, had medieval influences from the north, which are called Slavic but could well be something more generically Balkan, and are further north than Iron Age Greeks has not yet been fully disproved.
Many of you, though of Italian ancestry, were born and raised abroad. I was born and raised in Italy, and honestly today the relationship between Italy and Greece is almost inexistent, even the history of Italy and Greece is separated by many centuries. On TV you can count on the fingers of one hand the number of times Italian TV talks about something happening in Greece. Today there are more Italians living in Spain and Portugal than in Greece. Italy in recent decades has perhaps had more relations with Albania than with Greece.
Certainly Norway and Sweden have greater relations even today than Italy and Greece do. Identity is not something that is constructed on the basis of a DNA test. It may happen in the U.S., but it is unlikely to happen in Europe.
Ticinese people are certainly ethnically Italian, they are fully aware of this, but other than that they would never dream of switching to Italy they have lived in a multilingual and multi-ethnic context such as Switzerland for centuries.