I recently found the BEST MOUNT EV ER.
I've fought with suction mounts, bean bag mounts (which fall off in my lap during panic maneuvers) and big clumsy cradles and clamps for my phone.
Then I found this: At Amazon
It comes in several styles - some of them completely flat, some with articulated mounts, some with vent clips, etc. They provide several sizes of flat metal plates you mount on your device using 2 sided 3M automotive tape. If you use a phone case you can put it INSIDE the case back.
Then you stick the mount on the dash somewhere. They are quite small so mine fit right beside the radio on a Camry, and on top the dash on my F150.
The device (phone, TPMS, GSP) just sticks to the mount using magnetism.
It really stays - even on really rough roads.
And the magnet does not interfere with any of my devices - it doesn't effect an iPhone in any way - the compass, and all other internal circuits work just fine.
I have 2 on the dash of my F150 - one is articulated (like the link above) and hold my iPhone. The other is flat against the dash and holds my TPMS.
I also have one mounted inside the FW next to the monitoring panel and it hold my wireless indoor/outdoor thermometer.
If you want to take any device off the mount you just slide it off - no finding a release button or unclipping.
I LOVE these things - highly recommend them.
Here's a photo of my F150 dash with the Soche flat mount (just to the right of the emergency flasher switch) and my TPMS with the metal plate on the back. Ignore the bandaid - that was caused when 2 cement blocks decided to make a sandwich of my finger.
And here is the unit "mounted".
If you look way to the left of this photo you'll see my other mount - for my phone - right above the air vent. Only the base is in this photo, the rest is out of frame. This mount is glued to a special piece of hardware I found for the 2016 f150 that clips to the front of the dash and the air vent to hold the phone mount in JUST the perfect position. But I honestly wouldn't recommend this - it was a rediculoulous amount of money and the mount would have worked just as well glued to the flat space on the dash opposite where the TPMS is mounted.