Plug-ins should be available on the mobile apps. I think this is important, it is frustrating to have a different experience on mobile than desktop.
I also agree with the one person that said something about plug-ins being part of the app. I think things like the outliner tool would be great to include in the app.
Themes would be nice as well. For example, I see there is a theme for e-paper displays…which I could use on my Boox Air3c, but it seems custom themes are not supported on mobile devices…bummer.