PXE booting diskless image

Looking at the https://wiki.alpinelinux.org/wiki/PXE_boot (and the source of mkinitfs) I can see that configuration (apkvol), kernel modules (modloop) and packages can be installed over tftp/http when booting a diskless node from the network.

What is not quite so clear is whether booting a read-only preconfigured rootfs image (e.g. squashfs) is supported without having to use a NFS server. Has anybody tried to do something like this? I would ideally like to avoid the complexity of having a NFS server on the network...