Case in point: GrapheneOS (or any other custom Android distro) is unlikely to be able to ever pass remote attestation, even a signed, secure boot build with the bootloader relocked, because it's not the original OS for the hardware.
Same goes for any desktop Linux.
I still think destroying the playing field is better, but less likely to succeed.
This isn't about you attesting anything though. It's about corporations attesting that your device is 100% corporate owned. Can't have you running software that impacts their bottom line after all.
GrapheneOS could be the most secure operating system to ever exist, it doesn't matter to the corporation because it's still under your control. When they say "security", they mean "the corporation's security against the user", not "the user's security against the hostile world out there".