For those interested, I have compiled a set of instructions and scripts to address this problem, available here:
https://github.com/fdcastel/Hyper-V-Automation#windows-prepare-a-vhdx-for-qemu-migration
The provided scripts automate the process of taking a VHDX file, installing VirtIO drivers, and converting the VHDX to QCOW2 format.
https://github.com/fdcastel/Hyper-V-Automation#windows-prepare-a-vhdx-for-qemu-migration
The provided scripts automate the process of taking a VHDX file, installing VirtIO drivers, and converting the VHDX to QCOW2 format.