Instead of a full replacement of a UNIX box, what you really need is better replacements of key functionality than what exists.  File management, text editing, NFS server are the core functions.  A userspace program exposing an NFS server over wifi is the holy grail of phones, in general.  Fortunately, progress has continued & now there is something for PC.

https://github.com/nfs-ganesha/nfs-ganesha/wiki