I have Assassins Creed Odyssey on Playstation 4, but I want to play it on 4K Stadia soon, and now my question is, is it possible to keep up with my game progress?
No. Since Stadia has its own streaming you can only play Stadia games.
I know that, but can you transfer the game progress?
No. PS Plus can do that.
How do you mean?
If you have subscribed to a PS Plus subscription, the scores will be synchronized.