Comment by icebraining

No, Secure Boot doesn't check if the OS is supported, it just checks if it's digitally signed, and that the signature is valid.

And you don't even have to disable the check if you want to use an unsigned distribution: most (all?) implementations allow the user to load her/his own public key to verify the signature against.

While we should worry about its impact - particularly in certain implementations - it's really not even close.