What happens if you beat the 8-bit intro level in The End is Nigh?

When starting a new game in The End is Nigh, the game's opening is presented as a Let's Play video of Ash playing his favorite 8-bit game, The End is Nigh.

The player is clearly expected to fail here, because soon as you die a single time the game crashes and renders Ash's cartridge unplayable. This means you only get one try to finish the level.

Is it possible to beat the 8-bit intro level? What happens if I finish it?

Yes, it is possible to beat the intro level

(but holy smokes does it seem like a piece of work)

Beating the intro level on Steam will unlock the secret achievement Streaming Mimi. The Nintendo Switch has no trophy support, so it is unlikely you are awarded anything other than satisfaction.

Here's a video showing full completion of the intro.