[Klathmon]

Don't most bios have a password protect option? That alone makes evil maid attacks significantly harder.

[sanlyx]

That's the way to go I guess. But secure boot has obvious advantages in comparison. As a rule of thumb I do not trust any client-side "authentication" or passphrase input as long as there's no crypto involved. In legacy BIOS this passphrase can be bypassed easily, for instance

[Klathmon]

Yes, but it's not either-or, both can be used.

Combined with a TPU that wipes keys when secure boot is enabled/disabled gives a pretty secure system, that still allows you to "eject" to an unsigned boot when needed.