I can install Linux or Windows or even BSD on my laptop without much hassle, and get the updates directly from the OS vendors.

This isn't the case for smartphones. You don't have choice over your OS. You don't even get android updates directly from Google, and have to wait for device manufacturers to release the updates. Why is it so?

I've been thinking a lot lately about the future of software and where native apps and the web will reconcile and I had the idea that what if "the next OS" had a OSS federated app store that people and organizations could host themselves, but the system still used the app store model that pull app/program listings from all the installations online? This could apply to mobile or desktop computing, or even any of the other platforms (see windows store system compatibility).

After trying windows 10 a few years ago and disabling all the marketing stuff and disabling other features that hinder performance, I've been curious why my only other real choice is linux, or reverting back to windows 7.