I mean yeah sure, third party apps on android have a strong security model but what's the point when GrapheneOS is the only rom making updates on time, the play store runs as admin and manufacturer apps and driver can do whatever they want?

The OS is borked even before you install even a single of these highly sandboxed third party apps.

While in theory that model sounds great, in practice the security is worse than your average Linux distribution and the only people which managed to make it work is the GrapheneOS non-profit representing less that 0.1% of the devices.

(And ironically the only secure Android rom doesn't fully pass Play Integrity)