The reason I support the UBports project is because I believe that the current duopoly of mobile operating systems isn't helpful for anybody. I also think that Google and Apple collect way too much information on their users and aren't open enough about what this data contains and what it's used for.
In order to become a daily driver, Ubuntu Touch would need to be stable, updatable on device, use minimal battery life, and have a stopgap system in place to allow android apps to run if they're absolutely essential. Of course this android app compatibility would only be a temporary measure until the native software selection became more robust.
Perhaps linking into the Amazon app store or F-Droid might be a good plan?
However I'm not a developer so I don't fully understand the complexities of running Android apps on a mobile Linux environment. I would fully expect a lot of fiddling to be required to make an app compatible, and perhaps what would be needed is a seperate, user maintained repository of compatible android apps and installation instructions.