Hello here,

1. Do you have the list of languages you want ?
2. Flags are known to not match languages and even can be politically problematic for some languages. Better to just use the iso code.

To find the suitable list, you can combine ChatGPT or Spinash SPARQL agents, and ask them :

Please could you give me the list of all active wikipedia's iso code, their language in English, and their local language label.
Please use the following format : { iso : 'it', language: 'Italian', native: 'Italiano' }

Wikimedia may also already have such json quite everywhere. cc @Amire80