A new report called 'Count of Computers by Boot Mode' was released in 8.7.2
How can this report be used to determine 'Secure Boot State' for managed computers?
ITMS 8.7.2 or later
After running the new report 'Count of Computers by Boot Mode', you will notice only 2 rows of information returned. One for BIOS based computers and one for EFI. However, the report doesn't appear to show secure boot information.
However, you can further drill into the report for each machine type by selecting either BIOS or EFI, click 'Actions' > 'Computers by Boot Mode'