The winners of League C have been decided, along with Greece the other group winners are: Turkey, Georgia and Kazakhstan. These 3 along with Greece will be promoted to League B for the next edition of the Nations League.
Furthermore, they are potential opponents in the event Greece doesn't directly qualify for Euro 2024, in the playoffs. Of course if any of those group winners qualify directly they would also be replaced with lower ranked nations in the playoffs, so we may end up avoiding them all together.
As things stand assuming none of the 4 qualify directly, we would have to beat 2 of Turkey, Georgia and Kazakhstan to qualify for Euro 2024. The format is a one-off playoff game, 2 semis and a final with the winner gaining qualification.