I prefer TPU over hard plastic. No idea about this brand, but something like this:

https://www.amazon.com/HEYSTOP-Compatible-Nintendo-Protective-Protector/dp/B089KL3FDD

It would be pretty unwieldy, but any suction cup/sticky phone mount would be able to attach to the rear of the console.

Though to keep it dockable, I would recommend using something like a thin case on the Switch tablet portion, and then attach the phone grip to that rather than the backplate directly.

Something like this would be easy to remove and put back on;

https://www.amazon.com/HEYSTOP-Compatible-Nintendo-Protective-Protector/dp/B089KL3FDD/

https://www.quadratec.com/p/scosche/universal-extendo-telescoping-phonegps-windowdash-mount