Hi Andres Soncini,
Yes. The functional consultant works with both - the ABAP developers as well as the infra team.
First, the functional consultant lays down the requirement that encompass which mobile device is to be used, its model number along with the screens required, from where the data needs to be displayed and how it will be processed.
Once that is finalized, the FC first works with the infra guy to establish an ITS Internet service using the device configuration and creates basic settings for all the pages that will be used inside this internet service. This establishes a foundation and an URL for the ABAPer to do his tasks.
Then, the ABAPer, using the functional requirements specified by the FC creates programs and HTML templates under the above mentioned Internet service and tests using the URL mentioned on a local web browser on his machine (This may be due to unavailability of the mobile device at the developers location).
The functional consultant finally tests how the solution executes on the mobile device and delivers it to the business.
Let me know if you have more questions.