The only way to apply any pressure is to make them lose marketshare.

You’re literally going to need a large consortium of “public interest technologists” (Something like Futo plus Graphene on steroids) to get together and bankroll the manufacture of new hardware that supports something similar to the Google Titan M2, plus unlockable and relockable bootloader. As I understand that will be no small feat because of the engineering required, and because all device vendors are competing for fab and production line space with all the other established device manufacturers.

Then you need robust degoogled OS options, likely based on AOSP, that can pair with that hardware.