The short answer is pretty much yes. The door is very close to the end of the game.
If you want to try the game again, you might want to try to beat it with the least amount of upgrades possible or to beat it in as little ingame days as possible (you will be told how many days and hours it took you at the end). Then it might be more of an interesting challenge to replay the game.
For more spoilers read below 😉
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SPOILERS BELOW
After you open the door you reach the mountain and can climb it in a slightly more demanding and longer platforming section. On top of the mountain you get the final villager. And then there's a little surprise at the very end 😊