Tbh GrapheneOS.

Android is Linux.

And unlike desktop Linux it was able to spread secure and private standards

• every app is sandboxed, not some opt-in like Flatpak
• apps start with no permissions (or at least very little), everything is opt-in
• it is like 99% unbreaking, immutable, it just always works while my desktop Linux broke all the time
• there is a webview, which can be hardened. Not Electron, which is insecure and bloated
• energy saving etc work like a charm. 1% battery loss over an entire night!
• hardware security with trusted element is decades ahead of desktop Linux (Ubuntu is just now getting TPM encryption support)
• it is a unified platform, with tons of apps, many of them essential (as the platform is so secure), like 2FA, Banking, public services etc. you can have a full FOSS phone though

I am sure excited for other operating systems but they are just toys. GrapheneOS does amazing work that is a 100% alternative today, for real phones with normal prices, good performance and outstanding security.