We manage a commercial property and each time tenants move in or out, we had to call the sign guy to change the directory board. That sign shop will be going away soon and we want to end our dependence on an unreliable third party.

I called up a few companies for digital displays, and they all want to charge thousands. Most of that $$$ is going to the fancy marble surrounding the screen set flush on the wall or some new age monolith in brush stainless steel standing at the lobby. On top of that, there's a subscription service attached. We have to log on to their portal to update the board. The selling point is the directory can be updated while I'm sitting on a beach sipping on a margarita.

We don't need fancy stuff like that. All we really need is an old laptop at the lobby front desk, connected wirelessly to a decent size display hung on the wall. Something simple and clean like this:


The hard part is finding the right app to run on the laptop. The owner of the building does not want a touch screen display, so it needs to be scalable to potentially list up to 70 tenants. If there are currently only 25 tenants, we would not want 45 empty lines on the directory. That 25 lines should take up the entire screen. It then adjusts by scaling up or down in display size to accommodate changes in occupancy. Showing time, temperature, and weather for the next five days would be nice to have too.

Just run a PowerPoint slideshow continuously?

'Kiosk mode' will get you info for what you want to do, be it laptop or input-less option (rapberry pi, etc)
How complex or simple is up to you. A static image would be simple, and could be set up to be easily editable with a little more know-how/complexity. Adding web widgets like weather gets more complex.

My suggestion:
Raspberry Pi Zero with a webserver serving up a HTML Page. Boot the Pi into Kiosk mode & it will launch the browser full screen into the page. Display of your choice - if it has USB, it can probably power the Pi Zero (a full-size Pi will likely tax a basic USB).
I'd choose the HTML path over a static image for the editability. You can use excel to save a list in .csv & if you have the HTML set up right, your scaling is easy. It will also be the base if you get a wild hair & want the weather displayed or some other non-static content.

You'd need a keyboard & mouse for initial setup, or you can create an OS image with Wifi & Remote access credentials, then manage the rest remotely.
Pi Zero Kiosk
Not exactly how I'd do it, but simple & from a reputable source.

Flat screen tv with a USBport that will read a PowerPoint PPTX or PPSX file.

Create a PowerPoint presentation and save to the USBthumb drive.

Plug it into the TV USB port and set the TV input to the USB input source.

Use the remote to select the file and play

Going the TV route might make the use of dual monitors a challenge. A Pi or other SBC (Single Board Computer) with two HDMI ports will likely be the best option, with a Mac Mini a more expensive but versatile route. The Pi will beat the Mac in price, power, and OS updates, but will probably be easier to administer and find a programmer for support when direct HTML editing of the tenant list isn't enough.

I have set up lobby displays for clients for many years. Designating the right person to "own" the display, who is committed to making timely and accurate updates is your most important decision point.

Another key element is the ability to use a remote. In most cases I've worked, a Screen Sharing approach is far superior to the limited configurability provided by an IR or RF remote, or occasionally-attached keyboard/pointer combo.

We use a Samsung frame tv with a laptop connected. The tv is very thin with a remote brain box making connections and power easier for us. A single thin cable connects the screen to the brain.