I personally stand by as the note 9 being the best dex device for a cyberdeck. Headphone, USB c, s pen, wireless charging, cheaper to get, no notch, etc. Im certainly a little biased from having a note 9, but honestly the issues with other phones is they lose ports and such or compromise in other ways. The biggest compromise of the note 9 is probably the camera. It's a pretty good camera but the newer phones cameras are much better.

The best idea I came up with for a cyberdeck are like the Asus pro duo laptops with a screen on the top and one on the bottom with the keyboard. Just get a portable monitor and mount it as the top and use the phone as the bottom screen. Hook it up to a keyboard bottom and you create your own cyberdeck pro duo. I use my phone as a phone and haven't built a note 9 cyberdeck yet, but I do use Samsung dex and like it a lot. I hook up Bluetooth mouse and keyboard to my phone and plug it into monitors to do some photo editing and such on my phone without needing to export them to my pc and back to my phone.