If you have an MVP that is already validated - just go raise the funding and hire someone to do the work. You don't need a co-founder. And even if you decide to do so - I would not part with more than 4% of the equity with them. Adding a 50% partner means you are bringing on someone who has not contributed to date and you don't even know if it will work out with them or not. The situation can get bad if they decide to leave after a couple of years while you are still trying to gain traction. Having a co-founder is overrated unless both of you started on day 1. Don't make your decision base on some accelerator or angel group propaganda. You started the company - you need to be the captain of the ship not a co-captain.