I found a project "OTP Generator for N900", it is a native app written in C: https://github.com/jwhitbeck/otpn900
Currently it looks like it is only in extras-devel and extras-testing repository. Is there any chance to have the app in the stable extras repository soon?
Otherwise, does someone recommend another OTP app that is in the stable extras repository? I did not find any through the downloads search.