I am from Turkey, with three grandparents originally from Balkans.
I did 23andme test:
87% Balkan
8% Italian
4% broadly Southern European
0.5% Middle Eastern and North African
0.2% Yakut
I expected a more diverse mix. I was surprised there was no Eastern European and very little middle eastern. I suppose Eastern European in 23andme coincides with Northern Slavic. Not sure how come the Turkish grandparent didn’t pass on to me any middle eastern. It is what it is.
GEDmatch didn’t add anything, top matches with various algorithms were Greek, Bulgarian, and Italian.
So I think most Balkan Turks may be more Balkan than Eastern European, similar to Greeks and Bulgars.