I have 2 Questions beforehand:
1: With mobile apps you hopefully mean Mobile Web Browsers, if not please specify which apps
2: Which Typo3 Version does it currently use ? I would need at least Typo3 6.2
Now to my Reference, i am a Computer Science Student and also work at my University as Typo3 Sysadmin since nearly 3 Years, so i can say, that Typo3 is not an unknown CMS for me. My approach would be to make a new Fluid Template that will be loaded, if the User-Agent is a Smartphone. This Template would be based on Bootstrap and probably ( depending on your Desktop design) would not look like on Desktop.
If you like to contact me, please to it through Freelancer first