Currently to install Windows you need to repack it with Distrobuilder.

I propose adding method similar to how Proxmox does it. This means allowing user to mount ISO via device supported in Windows installer. User then installs vioscsi drivers from ISO and can continue installation on virtio-scsi disk. https://pve.proxmox.com/wiki/Windows_10_guest_best_practices

This would mean adding support for IDE or AHCI device. These are not hotpluggable so they would likely need separate handling from already established options. On the other hand these devices could be used for mounting Virtio ISO directly into Windows installer.

I tried to find any other method that would be hotpluggable and also work in Windows installer, but no luck.
Maybe XHCI controller with usb-bot or usb-uas devices that attach to SCSI device (scsi-hd, scsi-cd). But I am not sure if this works without virtio drivers.
https://qemu-project.gitlab.io/qemu/system/devices/usb.html

Thanks.