The mashups can be accessed by a mobile device and you can interact with them. Once said this, of course if it aren't designed for a mobile screen it won't work well for user experience.
Having a real good UI experience it will be hard to reach with standard TW Mashups, better you go with a native mobile App or a Progressive/Web App using TW API to interact with TW Backend. If it's really a simple interface TW Mashups may do the trick, but you will need to add some custom headers on the Mashup in order to make it work properly as a "web app", TW support team has an extension to set that simple headers ask them.
Best Regards,
Carles.