Investors are not dumb. The current duopoly is entrenched and merely asking for money to create an alternative os won't give you investment. Microsoft and Nokia among others failed big time even though they had plenty of money and competing operating systems. Investors give you money if they think you will be successful and return a multiple of that investment within a reasonable timeframe.
You need to solve the 3 player problem before you even ask for money: getting device manufacturers in even though you have no operating system, no devs and no users, getting devs even though you have no operating system, no devs, no users and no devices, getting users even though you have no device, no operating, no devs and no apps.
You need an MVP that shows promise towards all the above if you seek money.
This is like taxi on demand app business or the takeaway delivery business but with more players and with a higher minimum funds requirement. Plus the fact that unlike taxi apps or takeaway apps, choosing an operating system is a zero sum game so you are competing in the most direct way against well known and well established brands like iOs and Android who are funded by the richest companies on earth. Unlike Uber vs Lyft, where a user can install both and use both, your battlefield only has one victor. And given that other companies with more funding that you will ever see in your lifetime still failed, you have a virtually impossible task of explaining (before they even consider giving you a single cent) how you are going to be able to capture market share with your own solution to the 3 player problem.
Nokia and Microsoft only understood this right at the end: to avoid losing in the mobile os market, you need an ecosystem. Miss any of the elements and it all crumbles. Read Elop's memorable Burning Ship note on the final days of Nokia.