This project combines an ESP8266 processor with a 4x7-segment display, such that we can operate as an NTP-backed clock.
The code is self-contained, and described on this project homepage:
Once compiled and uploaded the project will attempt to connect to your
local WiFi network. If no access details have been stored previously
it will instead function as an access-point named NTP-CLOCK.
Connect to this access-point with your mobile, or other device, and you can select which network it should auto-join in the future.
(This "connect or configure" behaviour is implemented by the excellent WiFiManager class.)