Every single modern x86 chromebook has coreboot support.

That said: most if not all of them require some proprietary bits to initialize ram timings and to run the security coprocessors (Amd PSP, Intel ME).

Older intel based systems (like the Lenovo x200) have coreboot support that can work without the ME firmware (but still requiring the EC firmware).

A list of many of the google devices with coreboot support (note: they're all codenames, not marketing names): https://doc.coreboot.org/security/vboot/list_vboot.html#goog...