two things,
the version of qtopia that ships with the Zaurus is archaic, ie, its very old and doesn't support a lot of the newer qtopia features.
debian does already work on the Zaurus, ie PocketWorkstation. It does not run "natively" because nobody has taken the time to package it up as a flashable image yet. PocketWorkstation does not have its own kernel so it cannot be booted directly right now. Also, since it uses glib 2.3.2, most of its packages can not be installed directly to most Zaurus distros because most of them still use glib 2.2.x. I believe OpenZaurus uses glib 2.3 as well, but I am not sure since I have not used OZ yet.