Screens work over cellular, with two constraints worth understanding before you commit to it.
You need a router, not a modem
You cannot plug a USB modem into a player. Use a 3G, 4G, or 5G router, and connect the player to it over ethernet where possible, or Wi-Fi otherwise.
The reason is the sheer number of modem and carrier combinations, which we cannot test or support. A router turns that problem into an ordinary network connection.
Any router that provides an internet connection over ethernet or Wi-Fi should work. Availability varies by country, and we do not endorse specific models.
Plan for the data
We cache aggressively, and video and images are still large files. An idle player uses very little, but a playlist of HD video on a metered plan is a different proposition.
See What the network needs for the traffic figures we have measured, and size the plan against your actual content rather than the idle number.
For fleets, IoT-focused carriers are worth looking at alongside consumer plans.