Not related, but at first glance it looks similar. However, it appears that ruby-packer uses a library to access the squashfs image rather than actually mounting it. This makes it difficult (probably impossible) to load .so files from the squashfs file without having to copy them externally or to carry other helper executables along inside the image without also having to copy them externally to invoke.

A big goal for XAR is to be utterly transparent and not require hooks into Python, Node, or other runtimes to function.