GrapheneOS made clear they don't want to support anything bit Pixel devices countless times if I am not wrong and it's creator is anything but cooperative!
Do not buy preloaded LineageOS or /e/ OS phones or any Android phones without proper Verified Boot support and firmware updates. These devices also have no way for you to check whether they've been tampered with.
I'd note: just installing lineageOS or /e/OS already triggers the boot tampered message. You're already going to lose the ability to check as it's already deviated from normal stock. Having a phone that omits this feature makes no difference.
there is a difference between no verified boot and getting the this device is loading a different operating system message. for example, grapheneos has verified boot. anything other than stock will result in that splash screen though.