I fail to see how data privacy and data ownership are an issue when using iOS. I think Apple does a pretty good job there protecting their consumers' data, even from law enforcement agencies. Most likely, this is because Apple's business model is not built on data and advertising as opposed to Google. iOS itself does not bleed your data back to Apple for the purpose of re-selling it or running a business model other than selling a shiny device.

Now, looking at Eelo, what are you going to achieve with that, other than replacing iOS with something else? Are you replacing Google Drive? Are you replacing Google Mail? Are you replacing any other Google service? What are Eelo users going to use for email, search etc.?

The problem you're trying to solve (data ownership, data privacy) is not a problem of choosing a free and open operating system platform, it's a problem of choosing service platforms (for mail, search etc.) which do not operate on owning and selling its consumers' data. Since you're looking into building an operating system, how do you solve the problem you're describing?

I must be missing something here.