what if I want a Linux ... that doesn't manage a local file system or local storage at all [but] operates solely using the network, solely using a distributed file system
Linux can boot from NFS although that's kind of lost knowledge. Booting from CephFS might even be possible if you put the right parts in the initrd.
NFS (now that I think about it!) -- brings up two additional software engineering considerations:
1) Distributed file system protocol.
2) Software that implements that distributed (or at least remote/network) file system -- via that file system protocol.
NFS is both.
That's not a bad thing(!) -- but ideally from a software engineering "separation of concerns" perspective, this future software layer/level would ideally be decoupled from the underlying protocol -- that is, it might have a "plug-in" protocol architecture, where various 3rd party file system protocols (somewhat analogous to drivers) could be "plugged-in"...
But NFS could definitely be used to boot/run Linux over the network, and is definitely a step in the right direction, and something worth evaluating for these purposes... its source code is definitely worth looking at...
Linux can boot from NFS although that's kind of lost knowledge. Booting from CephFS might even be possible if you put the right parts in the initrd.