[negroni]

I had the same issue with ProctorU. Installing Windows on a 64GB USB and booting off that anytime I had to take an exam solved the problem to my satisfaction.

[notreallyserio]

I suppose I'm extra paranoid because I have a dedicated (older) computer for courses that require some sort of installed software, including Zoom. I don't want my unmounted hard drives available to the software.

[nisegami]

I suppose the alternative would be unplugging them, but your approach works too.

[blibble]

lock the disks using ATA commands then unlock them later

[sjcoles]

Still gives access to the EFI firmware. Hard pass.