@maat @nixCraft AppArmor and SELinux aren't really comparable to Android's ssndboxing model, which also handles app signing and certificate pinning.
Android's sandbox does not suck (bold of you to say when most Flatpaks can escape the sandbox by editing your .bashrc), Google just requires OEMs to bypass it for Play Services to obtain CTS certification (required to use the Android trademark). Alternate Android-based OSes are very secure (as long as they keep up with security patches, /e and iode do not). GrapheneOS's sandbox for it resolves this issue, letting you use it for apps that need it without security compromises.
A lot of Android's security also comes from verified boot (OS image is read-only and signed, bootloader checks the hash against the one burned in at manufacture or stored in the secure enclave at boot to ensure nothing is compromised) and a hardware secure enclave (which is not a TPM chip, its better)
edit: contact scopes (which GrapheneOS has had for ages) are coming in Android 17 to fix that issue.