"Excuses" are all security related: https://grapheneos.org/faq#future-devices

The project's Twitter account has already stated they want to use Samsung phones, but the hardware security isn't accessible for custom ROMs.

We know Samsung suck, though (The Samsung Galaxy S22 was just hacked in 55 seconds — yikes. Maybe the hardware sucks too, not just the software, so who knows.

You don't. But you can create another email under your account that's not obvious (like a93729472@proton.me). I mean law enforcement would still get to your account, but some random person who got your phone wouldn't be able to identify you with it. And use it to log into the VPN app as well.

You can also protect all Proton apps (except the VPN) with pin/biometrics