I've just upgraded Windows 10 to Windows 11 following the guidance on the Parallels website.
I used a separate Windows 10 install rather than my main install - just in case
All went according to plan - did have to use the 'AllowUpgrade.reg' feature though.
Note that your existing Windows 10 needs to be 64bit and you need to be running Parallels v17
Installed FH6 for testing purposes (don't want to transfer my v7 licence until I've done more testing).
All in all, everything went very well.
I use Oracle Virtual Box on my MacBook and I'm not sure if that handles Windows 11 yet.