For Proxmox and libvirt users, the virt-builder tool added Windows 11 templates in late October 2021. This command downloads a minimal QCOW2 directly:
In 2021, the best way to obtain a Windows 11 not through a direct download from Microsoft windows 11 qcow2 download best 2021
Zero risk of malware; full control over TPM 2.0 and Secure Boot emulation. For Proxmox and libvirt users, the virt-builder tool