Online changes in a singleplayer game?

I’m working on a singleplayer project, I want to have the ability for a player 1 to leave a note or a static mesh in the map but when ever other player e lets call him player 2 enter the same game in he’s map the static mesh or the note would appear.

Now I guess it should but some how connected to some kind of online servers like through steam or epic.

Would it be hard or too demanding?
I’m not asking it to even be happening exactly in the same time just after a player close the game and enter it again

Thanks!