I want to try to replace the original bios for one that is better fit for linux; I found these two references, on wikipedia thou. They are projects, but that’s about it.
I bought a Protectli mini PC from their website because it offered the option to pre-flash coreboot on it unlike the ones sold through Amazon. Honestly I can’t comment much on coreboot though because it’s currently acting as my router and I rarely reboot it.
Flashing the BIOS can be risky.
Have you confirmed if your old Asus laptop even supports an alternative BIOS?