And that's before you consider things like Docker, which will let you run linux software just about anywhere including windows, mac, BSD, etc. On the desktop we have things like Snaps, Flatpack, etc. Also consider Steam running games made for windows on Arch Linux, and Apple running software compiled for Intel on ARM. Windows 11 will run Android applications apparently. And of course WASM is the next level in portable executables.

The OS as a control point for where software can be installed and used is increasingly less relevant. It's increasingly about controlling the application stores and maximizing their reach rather than the OS platforms. Mobile is actually lagging behind these trends a bit; mostly because of draconian app store policies discouraging/forbidding anything that is "not native".

It will be interesting to see if Fuchsia will get a lot of adoption outside of Google. I'm very skeptical about their ability to convince others to use this. Even their strategy around Fuchsia remains murky. E.g. their whole IOT strategy resembles what they are doing with messaging in terms of quickly abandoned things that they announce with a lot of fanfare every year. One of these train wrecks is Nest, which they picked as a niche player guinea pig for the first commercial rollout of Fuchsia. I doubt it will move the needle for Nest. Or for Fuchsia.