FR airports
Lappeenranta mentioned, I've tried to be quiet, but as I live in Finland...
Admittedly it is one of the opportunities bypassed by FR. Russians do come to fly from Finland, mostly using their own cars, we see them even at Tampere airport – and it's a place much more apart from Russia (the distance from St. Petersburg to TMP is appr. 470km versus 190km to LPP/EFLP).
Once I wrote here something like "is MOL blind not to see the potential?" But then I started to think different: maybe FR wants more than just to fly the full planes? Who would actually pay them so called "marketing support"? Hardly the city of St. Petersburg to prop up the flights to the airport located on the Finnish side of the border or Lappeenranta commune to promote Russians travelling to Western Europe.
While Ryanair's economy is a bit complex, the place is worth giving a try (say: "Come to see Saimaa Lake and the Treasures of St. Petersburg" or so, it could work) .