[crabbone]

My very recent story with libvirt and secureboot resulted in blanket disabling of secureboot as part of the preparation for creation of VMs.

The reason: the VM refuses to boot when provided with an ISO (via virtual CDROM) with a meaningless error (permission denied: go figure out what permission and why was it denied and by whom).

Secureboot is meaningless / useless for most people running VMs, be it on own or rented hardware. It takes some pain and extra work to get it to work sometimes, and a huge amount of work to get it to work always. I doubt anyone was dedicated enough to get it to work always. So, I believe you are right. This is extremely unlikely to be a problem for anyone running Linux VMs, and the more VMs they need to run, the less likely it is a problem.