rsync client for Chrome OS?

[Perry Hutchison]

Having found no mention of Google's Chrome OS in the rsync archives,
nor any useful* pointers via Google, I'm wondering if anyone here
knows of an implementation of rsync client for Chrome OS in normal
(not developer) mode, i.e. as an app or extension.

* It seems that rsync is available in "test" builds of Chrome OS, but
  not in normal release builds.  As far as I can tell, installing a
  "test" build requires putting the device in Developer Mode, which
  requires doing a "powerwash," which wipes local storage -- totally
  defeating the purpose of installing rsync in the first place.

* rsync is available in Termux, but presumably would only have access
  to the Termux container, not to the user's Chrome OS configuration
  or files.