But this idea or ones much like it have been presented before...
"Hassle-free diskless Virtual Machines with Xen and Alpine Linux"
https://jonnytyers.wordpress.com/2016/08/16/hassle-free-disk...
"How to make a Diskless Virtual Machine (KVM)"
https://github.com/lispydev/diskless-kvm
And if you just want a dead easy PXE server for bare metal...
https://www.iventoy.com/en/index.html