There is a Boot Menu available with the pc and q35 machines' BIOS that can be enabled with the QEMU parameter -boot menu=on (I have personally verified that this doesn't work with the Tianocore EFI BIOS).

I would like to be able to turn on this boot menu for my VMs in the "System" configuration. This way I don't need to worry about the boot order and can override it when I need to. However I feel like the boot menu should not be enabled all the time, as it slows down booting the VM when I don't want to override the boot order.