This is really important. Windows needs an extra driver for fastboot (aka bootloader) mode, so the phone really has to be connected while being in fastboot mode.
Windows 11 itself shouldn’t be the problem, I’m using it myself and ADB as well as fastboot are working just fine.
And if the phone is recognised in general on the Windows side, USB passthrough in the virtual machine seems not to be the problem either, or are there settings or permissions or anything for USB in Parallels?
The internet says …