The stand is made by Reyburn Tools: https://www.reyburntools.com/products/cyberstand
It is rather expensive as stands go, but, it has worked in every situation, whether placing it on the tuning pin in a grand or upright, or standing it over the treble bridge on a grand. I have recently purchased the iPhone 17 Pro Max, and it does fit that phone with the Apple case installed.
There are extra parts included with the stand, such as an extra spring, and I even think you can change the sliding post size. They use piano lifesaver style clips that are curved, so when the phone is in the mount, the clips do not press up against the volume or other buttons on the side of the phone.
I have tried many other stand through Amazon, and they were nice, but they tended to be heavy didn’t have the tuning pin extension etc. You can use the phone in portrait or landscape mode. I have gotten used to using it in portrait mode, it not only allows me to see the tuner better but then I can really direct the microphone right at the note I want or over the note on the bridge.
I can't seem to get my photos to upload, but Reyburn's website has a few.