Nixie tube clocks have been around for a long time. The Millclock ZIN-18 Nixie Clock can be controlled with a smartphone app. It has gorgeous digits to show time in 12/24 hour format. It comes with a convenient touch control system. The companion app allows you to control the backlight, time format, and other lighting effects.
The Millclock ZIN-18 Nixie Clock is compatible with iOS and Android devices over WiFi. You can find out more about it here.