It's not hard to get 2M at the beginning of the game. When you buy the key, you keep it. So just restart the story.
By beginning of the game, I mean when the player is new to it, their Frank/Chuck is Level 1. I don't know of a way to start with $2M and get the key, unless you're talking about TIR (which you hate) or having a co-op partner join, gift cash, quit, repeat, ad nauseum. I just mean that Frank can start, ignore the missions, do the Genocider two-step, and the player can max out levels, inventory, moves, etc. without ever USING them, then restart the story --with the Real Mega Buster, no less-- and play the game as a completely overpowered Frank and never experience the slow growth of the character over multiple replays, which is the point of the much-maligned Save system.
In DR2, there's no way for a first-time Chuck to do that, and it's a good thing.
Are you saying there's an easy way to start with $2M?