Hi @gabor_nyul ,
The DeX is a nifty device. Unfortunately we don't have any current plans to support externally connected hardware on mobile just yet, but we can leave this post as an enhancement idea for others to follow.
Well for a Tab S4 I just need a Type-C and HDMI converter and can go to any meeting room to hold a meeting using GoToMeeting as screen share. Unfortunately sharing only the tablet screen but not the DeX screen.
Would be great is this feature could end up on the top of your backlog. ;-)