https://www.cnet.com/news/samsung-dex-pad-galaxy-s9-touchpad-pc-mwc-2018-b2b/

I used last year's version, the DeX dock, to turn a Samsung Galaxy Note 8 into my work computer. The experiment worked better than I expected: I could file stories, use my company's browser-based content management system and access Google apps just fine. All I needed was a mouse, a monitor and Samsung's dock to bridge the phone into becoming a "lite" Android computer.

For 2018, the DeX Pad turns Samsung's new S9 into a touchpad driving a PC-style experience you can use with a plug-in monitor. The DeX Pad is only for the Galaxy S9 and S9 Plus for now, but it may eventually get an update that'll let it work with the S8.