There are so many country flag EMOJIs, that it is difficult to select one
from EMOJI list. There should be a country flag input function.
My requirements are:
  (1)accept several names for one EMOJI
     ex. United Kingdom, UK, U.K., Britain
  (2)accept translated names in local languages
  (3)accept ASCII characters for accented alphabets
     ex. Aland Islands as Åland Islands
I created such data and functions.
  (1) is done with formal names, common names, and other names in English.
  (2) is done with Japanese.
  (3) is done with completion.
Type M-x emoji-country-flag-search RET and input a country name,
a country flag EMOJI is inserted.

The prompt string may not be appropriate because I used #'emoji-search
internally for the purpose of listing of available completions.