For iApp LX F5 still primary uses the LX framework to make web interfaces and wizards like "SSL Orchestrator" etc., or AS3 integration, where if you BIG-IQ , iWorkflow or Ansible you can create services on many F5 devices similarly to the iApps services from central managment station (BIG-IQ, iWorkflow or Ansible).
https://clouddocs.f5.com/products/extensions/f5-appsvcs-extension/latest/
https://support.f5.com/csp/article/K89634428
If you have version 14.x or newer search the F5 downloads for the iApp RPM file and see for yourself that currently is available but for now most of the things will still need and use normal iApps.