I've never liked Minecraft until now. I just started playing, even though many people have tried to get me to play in the past; this game has been around since 2011 and remains surprisingly popular.
Minecraft itself is similar to a blockchain in a way that you can basically do anything you want in it.
Meanwhile, in a sandbox, there largely is no objective unless you boot up a mod that gives you one.
This is not always true. Many sandbox games have objectives. Even Minecraft has an objective. Survive. And some sandbox games (for example the Grand Theft Auto series) also have (even more complex objectives), like a full storyline with main and side missions. Although some sandbox games really do not have objectives, for example Garry's Mod.
Yes factorio has one as well: build a rocket to escape the alien world.
However, something I failed to mention is that these sandboxes will be modified within the metaverse.
There will be so many developers and content creators that sandboxes will have thousands of missions and campaigns.
The most popular ones will pay huge royalties to the creators/owners.