Like a sandbox? Running apps in a contained environment where you can limit what the apps can do. Android/ iOS does and GrapheneOS does it to a better extent (control internet, sensors, and file access etc.)

I think relying on some app store to protect you against malware is dated. A lot of OS' take an approach of hardening themselves in hopes when you somehow get malware it deals far less damage. Would also make the OS more difficult to exploit and make the budget for very sophisticated attacks go up.