Why do we must have any victory types at all? I think the best idea (also based on euro board-games) is to:
1. make a victory condition changing for each game
2. Composed of a few mini-quests (you will not be always focused on a one resource grind from the beginning, and you will have to use more flexible strategies)
3. Changeable overtime of the game. For example, at the start of the game you see the first set of mini-quests, after the classical era the second part, and after the industrial era the third part. So the game will be engaging in each stage of the game.
As I said, this silos-focused victory type is a blind and limiting road in my opinion.
@Zegangani believe me many board games, menage with win conditions issues better than a Civ 6. Deeper and complex victory conditions I understand as harder to master, requiring more flexible strategies and as resistant to meta-game as they can. It is achievable. But thirst of all let's get out of the ruts of this victory condition scheme we are stuck now.