Another try from me. If this doesn't work, I'll give up.
I haven't used VirtualBox recently, but I know that you have choices with a VM's hardware configuration. Can you change your VM's hardware so that it meets Windows 11 requirements?
I was actually surprised that I was able to install Windows 11 into Hyper-V on my 13-year old computer, which thinks TPM stands for tire pressure monitor. Clearly, the critical hardware was virtualized. Perhaps Hyper-V is more generous with hardware virtualization than VirtualBox?