Here's a little overview of the new DJI OSMO MOBILE Gimbal (for smartphones) as well as a test using the Moondog Labs Anamorphic Lens on an iPhone 6s. Since the arm on the Roll motor can be extended on the OSMO Mobile, this balances quite well without the need of any additional counterweights. It's just a tad top heavy but the OSMO's strong motors handles the load with ease.
Using the FilmicPro app to shoot video instead of the DJI Go App allowed me to configure the iPhone for real time Anamorphic DeSqueeze preview and also choose various resolutions and bitrates. FilmicPro has also been updated to support the OSMO Mobile so you can hit the record button on the joystick to start and stop video, and use the Capture button (normally for stills) to lock focus and exposure.
While many choices have already existed for gimbals that support iPhones, the new DJI OSMO Mobile already works pretty darn well with the heavy weight of the Moondog Labs Anamorphic Lens. Find it here (link).