Il tool non centra, centra cosa ci metti dentro ed oramai trovare una distro non firmata è un impresa.
Customizzi cosa?
Compili il kernel da te?
https://wiki.debian.org/SecureBootWhat is UEFI Secure Boot NOT?
UEFI Secure Boot is not an attempt by Microsoft to lock Linux out of the PC market here; SB is a security measure to protect against malware during early system boot. Microsoft act as a Certification Authority (CA) for SB, and they will sign programs on behalf of other trusted organisations so that their programs will also run. There are certain identification requirements that organisations have to meet here, and code has to be audited for safety. But these are not too difficult to achieve.
SB is also not meant to lock users out of controlling their own systems. Users can enrol extra keys into the system, allowing them to sign programs for their own systems. Many SB-enabled systems also allow users to remove the platform-provided keys altogether, forcing the firmware to only trust user-signed binaries.