How do I save persistant object?

hello, I would like to know if it was possible to save persistent objects in the local storage. indeed I have a layout which acts as a world for my game and by finishing a quest we destroy an object which prevented us from moving forward. by changing layout and returning to this world, the object remains destroyed. however, if you save and restart the game, the object will reappear. would it be possible to keep this object destroyed? and conversely to keep objects created during the game?

When you save the game it saves the current state of the game including persistent objects and ones that were destroyed. I don't know how you managed to save after one was destroyed and load and it had returned unless you loaded a different save game.

i use dictionary to store game data like health or money, which i save to local storage, i don't use built-in save

Time to move onto the system save then, there's no downside.

I tried like that but when I load my game my player is at the place where the game was saved and not at the last checkpoint, moreover the music does not start from the beginning

The game should be saved only at checkpoints then? If you want music to start from the beginning and not at the point where you saved you can always set up logic on game load to start the music again.