For what it is worth, I have the same requirement as Andreas and am using libvirt/qemu to build a virtual with UEFI. I’ve found this works reliably and is a single option in the settings when creating a new VM using Virtual Machine Manager. (I try/test config changes before changing the config on my host, and main, system)
I had an issue with a Manjaro XFCE virtualbox VM ( Manjaro XFCE Unstable host) yesterday. Due to the repositories changeover, I think. The system wants to upgrade packages that I know are in the official repositories to the AUR version(s). An example is menulibre, where it wants to install the same package with the epoch naming format. I didn’t want a bunch of AUR packages as substitutes, so I switched to Unstable. After I updated to Unstable, I couldn’t get scaling to work as it did before and I was seeing Virtualbox errors during boot and “stopping vboxadd.service” issue on shutdown. This VM is also a efi install that worked fine previously. I didn’t try too hard to fix it as it was just a test VM for my new computer (efi) install which I had never tried before. I have restored the VM from a backup and will stay on Stable until this repositories thing gets sorted out. Currently it needs 405 updates.