Same here, though ~6 weeks in my case. I will put up the documentation in the meantime but integration into the build scripts + testing will take a while. If anyone is eager to implement it as soon as possible then he/she should go for it.
I also tested it successfully with the gateway ( version 220.127.116.11.6 on bare metal + some drivers).
In case this will be implemented in the build scripts initramfs-tools would need to be removed since it can't coexist with dracut. Imho there should be no major problems regarding VirtualBox. Major distributions (Fedora, RHEL, CentOS) using dracut by default are supported by VirtualBox + guest additions. There are some bug reports but there are bug reports on anything and likely on initramfs-tools too ...
I dug somewhat through the build scripts and packages looking for initrd and initramfs and there likely need to be some changes.
Also there would need to be some check for at least the swap file generator if it runs on a live system. Parsing the kernel command line should be enough.
Otherwise a large swap file will be generated which just consumes a lot of RAM.