The apps you actually need to participate in society (digital IDs, banking apps, etc.) will never run on your homegrown OS. Having a billion dollars changes nothing about the fact that you need either iOS or a Google-blessed Android version.

Then perhaps we should have regulations to ensure that social participation is not locked behind these gatekeepers.

In particular, government and financial services should not require smartphones. Especially in an era when devices often require an “account” with the manufacturer that can be suspended or cancelled.