> You could retain ownership and rent it to your company. Sell it in return for debt, etc... For example maybe you sell your SaaS to the business for £20M then forever the company is repaying debt to you, instead of paying dividends.

This idea is very alien to me. Can you link to any concrete examples of this for something like a small solo SaaS company? How do I pick the price? Where is the purchase money coming from when I'm selling it to myself with a company that is starting from nothing? How do I decide between selling vs renting it? What stops this being abused to avoid tax?