The general consensus that mainland Greeks (aside from Maniots and SE Peloponnesians) are Balkan shifted is only partially correct. Yes many mainlanders cluster closely with Albanians but then there’s a significant West Euro shift towards Central Italy attributed to heavy ENF vs Steppe composition. Honestly other Balkanic pops including Bulgarians or Serbs don’t show much affinity with mainland Greeks unless we get specific to the Northern, outlying regions of Greek Macedonia or Thrace.