I wanted it to just be a destruction simulator, but the emphasis on speedrunning made it not so fun for me.
I have wonderful news! There's a mode called sandbox that's just for that.
If you go to the options in the Main Menu, under the "Game" tab, there's an option to instantly unlock everything for the Sandbox mode.
There's also an option to allow mission skipping, if you wanna go that way.
Oh that's nice! They must've added that sometime ago, huh? I think I only played a demo.