If he gets the right price for it, then he can finance a fleet to walk all over the British forces and set up one or more of his relatives as kings on those islands. Independent Ireland with a Bonaparte in power is almost guaranteed. With no England to defend it, France and the US walk all over Canada. The US gets Upper Canada, Napoleon gets Lower Canada. He probably grabs some other parts of the world held by the British.
The question here is if France can hold on to all of that AND it's hegemony in Europe. I can only see Lower Canada staying loyal like Louisiana and Poland did. Not so sure about Napoleon I's other gains.