The most critical item here is intellectual property. Who owns the idea? The company.

So you have a potential issue there. They are unlikely to want to give up any ownership share since they already own the idea.

Did you sign a non-compete agreement when you came aboard? How about the team members you're considering?

The fact of the matter is a spinoff will only happen if senior leadership at the company agrees it should.

Now, are you stuck? No. You can talk to whoever asked you to form the team, and sound them out about the idea. You can use the argument that you'll be creating massive value, and one of the ways to remunerate you for doing that is by giving you ownership shares.

You'll see pretty quickly what their attitude is regarding the idea.

Note that there may be consequences to "tipping your hand early".

As another possibility, if you did not sign a non-compete clause, you have the option of forming a competing company. You can get paid to learn, developing the original idea with your current employer. Then, with the experience of having lead the creation of the idea and knowledge of what to do, you can take that track record to investors. You may even be able to bring some members of the team along.

I leave it to you to decide how ethical that approach is.

In my opinion, without knowing your boss or the people above them, it is difficult to see an easy path to a spinoff. There is too much for them to lose by giving up ownership. They can simply hire a manager, especially after you've done the hard startup work.

If you had an owner like Felix Dennis, I can imagine him setting you up with an ownership stake, fuel for the fire, and shouting an encouraging, "Go!" But people like him are rare.

So don't put the cart before the horse and come up with intricate plans for dividing up the spoils. You have a big sales job to do first. If you want to discuss that, I'm available.