What's really interesting about @sys is that it supports a search-path at run-time, so the resolution can walk back through a list of target systems to find an available one.
You could do that, but @sys is resolved in the kernel - so you can use it in symlinks and just add .../bin to your path (with bin -> .bindir.@sys ) and thus it works for non path cases too...
Not as advanced as what Domain/OS did before it - the kernel straight up evaluated arbitrary environment variables in the path resolver, which they used for things like selecting "personalities" (BSD vs SYSV vs "native") but it wasn't restricted to any particular names. "We don't make them like that anymore..."
This sounds cool, but I've wondered - couldn't you just stick something like
in /etc/profile or so?(I'm actually doing something like this myself; I don't (yet) have AFS or NFS strongly in play in my environment, but of all things I've resorted to this trick to pick out binaries in ~/.local/bin when using distrobox, because Alpine and OpenSUSE are not ABI compatible)