Here are some links for you that I think would be useful for a related setup, however I can't speak for the user that posted that. The headless installation should follow the same principles of using a RAMDisk though.

https://wiki.alpinelinux.org/wiki/Raspberry_Pi_-_Headless_In...

https://wiki.alpinelinux.org/wiki/Alpine_Linux_with_root_on_...

https://wiki.alpinelinux.org/wiki/Docker

https://wiki.alpinelinux.org/wiki/Install_Alpine_in_Qemu

If you want to dive deeper, I have written a blog post about how to pxe boot alpine in your home (with central config storage) https://blog.haschek.at/2019/build-your-own-datacenter-with-...