If you can’t cost-effectively or cosmetically get a direct network connection to the digital signage player, what viable alternatives exist?”
There are aspects to this question. One applies to very small networks with just a few signs in one location. The other applies to larger deployments with more displays and multiple locations.
For the first type, there are options such as a display with a built-in digital media player. This could be a System-on-Chip approach or a slim-line media player that attaches to the back of the display. There are some units that combine a screen, a digital media player and content management software. These can be updated using a USB flash drive or an SD card – a more labor-intensive and operator-dependent system – but for a small retailer or restaurant with two or three signs, it would work.
For a larger network, where network connectivity is needed to keep all of the players updated with the latest content, Wi-Fi would be the obvious approach if wired connectivity isn’t an option. There are some displays and players with integrated Wi-Fi capability. This solution would be especially important in an historic building where running Cat. 5 cable through the walls could be problematic or in a very open environment where wired connectivity could only be accomplished by digging up the floor.