Not OP, but my buddy built a table with a recessed TV. On the DM’s side, there’s an HDMI splitter; One split goes to the TV, and the other goes to a portable monitor mounted next to the DM. So the DM can see what is on the TV, without worrying about rotating everything 180° to face the players.

The advantage of dual screens is that you can run multiple instances of Foundry on a single PC. So the DM’s main laptop screen (which the players can’t see) is the DM side, then a second instance (displayed on the TV and external monitor) can be the players’ view. It allows the DM to sequester the players’ view just like an online game.