Android and ANT+

I have an android phone which has ANT+ connectivity built in (Samsung Galaxy S7). I was wondering if I could somehow make the phone use an external USB ANT+ dongle instead. I have the cable I need for making this connection.

The benefit of this would be the ability to connect the external ANT+ using a long USB cable and position it close to the trainer for improved signal strength.

Yes. If you can set your phone to usb-otg mode. At least that is what I did with my previous phone that had ant+ built in.