Thanks for your suggestion.
I've considered building a custom solution as you suggest with a pi-zero. I'd need to 3d print cases and attach a simple LCD display. The option is also more versatile as one could add potentially NTP sync time via WiFi and perhaps add richer display.
That said, I'm looking something pre-canned and low powered. Developing a pi-based system would be a bit costly (time + money) for me at this stage.
I have seen a device that ticks a few boxes. Although seems a bit pricey and appears to require proprietary hardware to configure the devices: