Knowing what you shared so far as a stranger, I would probably negotiate heavily with your company to give you some sort of ownership in this venture while they

Knowing what you shared so far as a stranger, I would probably negotiate heavily with your company to give you some sort of ownership in this venture while they help you build/fund and hopefully market it. May be even get a lawyer who specializes in contracts, M&As and get their opinion if you can afford a few hundred bucks. Best case scenario: The company creates a separate subsidiary for this project where you are an equity owner/director etc. in that company but overall it is owned (majority ?) by the parent company. However, they give you the freedom to work on it while they provide you the security and comforts of the current job. Win-Win for both. If you succeed in this venture, your parent company gets a big piece of it. If you fail, you hopefully still have your main job. If you are serious and they are serious, get your own lawyer. Good luck!!