No, if you are using an audio interface then you might as well be using a desktop or laptop... I mean really, that is true. The beauty of Logic on an iPad would be the portability, and having to use your one usb-c port for headphones is truly weak, and having to bring along an audio interface as the alternative is a non-starter. I was about to go pick up an iPad Air this morning until I remembered the lack of headphone port.If you are using Logic Pro, in most cases your device is going to be connected to an audio interface.
It's one of Apple's only real screwups, getting rid of headphone jacks but not replacing with a (non-latency) alternative. They should've waited for the airpod technology to mature before they killed off the jacks.