In-queue displays are screens where people are already waiting. That placement is unusual and valuable: everywhere else in a venue, signage competes for attention against movement and intent, but a queue supplies a captive audience with nothing else to do.
It is the one location where longer content works. Explaining a product, upselling an add-on, or pre-empting the question customers ask at the counter all have time to land, and reducing what has to be explained at the counter speeds the queue itself.
The caveat is that perceived waiting time is the thing you are actually managing, and content cuts both ways. Engaging content makes a wait feel shorter; a visible countdown or position indicator that moves too slowly makes it feel longer, and repeating a short loop makes people notice exactly how long they have stood there. Loop length should exceed the average wait, or the customer measures their own delay in repetitions.
Mount for a standing eye line and a close viewing distance. Content designed for a wall across the room is oversized and awkward at a metre.