Secure boot helps protect against evil maid attacks by checking hardware and OS signatures. If the boot process has been tampered with, the user can be alerted that the secure boot process can no longer properly verify signatures.

While its probably true that you can no longer guarantee that system can be used safely ever again, at least you will be aware that it was tampered with and you can go ahead and send that system to e-waste and get you a new system.

i know this is not for PCs but GrapheneOS uses the Google Titan chip and this app to solve that problem.

might be a long time before we get similar hardware for PCs. the only thing that's remotely similar is the Apple T2 for MacBooks but there's no Linux distro with comparable security to GrapheneOS yet.

a raspi, soic8 clip and coreboot