All culture codes and corresponding Countries.

AllCultures.cs

public static Dictionary<string, string> AllCultures = new Dictionary<string, string>
{
    {"af", "Afrikaans"},
    {"af-ZA", "Afrikaans - South Africa"},
    {"ar", "Arabic"},
    {"ar-AE", "Arabic - United Arab Emirates"},
    {"ar-BH", "Arabic - Bahrain"},
    {"ar-DZ", "Arabic - Algeria"},
    {"ar-EG", "Arabic - Egypt"},
    {"ar-IQ", "Arabic - Iraq"},
    {"ar-JO", "Arabic - Jordan"},
    {"ar-KW", "Arabic - Kuwait"},
    {"ar-LB", "Arabic - Lebanon"},
    {"ar-LY", "Arabic - Libya"},
    {"ar-MA", "Arabic - Morocco"},
    {"ar-OM", "Arabic - Oman"},
    {"ar-QA", "Arabic - Qatar"},
    {"ar-SA", "Arabic - Saudi Arabia"},
    {"ar-SY", "Arabic - Syria"},
    {"ar-TN", "Arabic - Tunisia"},
    {"ar-YE", "Arabic - Yemen"},
    {"be", "Belarusian"},
    {"be-BY", "Belarusian - Belarus"},
    {"bg", "Bulgarian"},
    {"bg-BG", "Bulgarian - Bulgaria"},
    {"ca", "Catalan"},
    {"ca-ES", "Catalan - Catalan"},
    {"cs", "Czech"},
    {"cs-CZ", "Czech - Czech Republic"},
    {"Cy-az", "Azeri (Cyrillic)"},
    {"Cy-az-AZ", "Azeri (Cyrillic) - Azerbaijan"},
    {"Cy-sr", "Serbian (Cyrillic)"},
    {"Cy-sr-SP", "Serbian (Cyrillic) - Serbia"},
    {"Cy-uz", "Uzbek (Cyrillic)"},
    {"Cy-uz-UZ", "Uzbek (Cyrillic) - Uzbekistan"},
    {"da", "Danish"},
    {"da-DK", "Danish - Denmark"},
    {"de", "German"},
    {"de-AT", "German - Austria"},
    {"de-CH", "German - Switzerland"},
    {"de-DE", "German - Germany"},
    {"de-LI", "German - Liechtenstein"},
    {"de-LU", "German - Luxembourg"},
    {"div", "Dhivehi"},
    {"div-MV", "Dhivehi - Maldives"},
    {"el", "Greek"},
    {"el-GR", "Greek - Greece"},
    {"en", "English"},
    {"en-AU", "English - Australia"},
    {"en-BZ", "English - Belize"},
    {"en-CA", "English - Canada"},
    {"en-CB", "English - Caribbean"},
    {"en-GB", "English - United Kingdom"},
    {"en-IE", "English - Ireland"},
    {"en-JM", "English - Jamaica"},
    {"en-NZ", "English - New Zealand"},
    {"en-PH", "English - Philippines"},
    {"en-TT", "English - Trinidad and Tobago"},
    {"en-US", "English - United States"},
    {"en-ZA", "English - South Africa"},
    {"en-ZW", "English - Zimbabwe"},
    {"es", "Spanish"},
    {"es-AR", "Spanish - Argentina"},
    {"es-BO", "Spanish - Bolivia"},
    {"es-CL", "Spanish - Chile"},
    {"es-CO", "Spanish - Colombia"},
    {"es-CR", "Spanish - Costa Rica"},
    {"es-DO", "Spanish - Dominican Republic"},
    {"es-EC", "Spanish - Ecuador"},
    {"es-ES", "Spanish - Spain"},
    {"es-GT", "Spanish - Guatemala"},
    {"es-HN", "Spanish - Honduras"},
    {"es-MX", "Spanish - Mexico"},
    {"es-NI", "Spanish - Nicaragua"},
    {"es-PA", "Spanish - Panama"},
    {"es-PE", "Spanish - Peru"},
    {"es-PR", "Spanish - Puerto Rico"},
    {"es-PY", "Spanish - Paraguay"},
    {"es-SV", "Spanish - El Salvador"},
    {"es-UY", "Spanish - Uruguay"},
    {"es-VE", "Spanish - Venezuela"},
    {"et", "Estonian"},
    {"et-EE", "Estonian - Estonia"},
    {"eu", "Basque"},
    {"eu-ES", "Basque - Basque"},
    {"fa", "Farsi"},
    {"fa-IR", "Farsi - Iran"},
    {"fi", "Finnish"},
    {"fi-FI", "Finnish - Finland"},
    {"fo", "Faroese"},
    {"fo-FO", "Faroese - Faroe Islands"},
    {"fr", "French"},
    {"fr-BE", "French - Belgium"},
    {"fr-CA", "French - Canada"},
    {"fr-CH", "French - Switzerland"},
    {"fr-FR", "French - France"},
    {"fr-LU", "French - Luxembourg"},
    {"fr-MC", "French - Monaco"},
    {"gl", "Galician"},
    {"gl-ES", "Galician - Galician"},
    {"gu", "Gujarati"},
    {"gu-IN", "Gujarati - India"},
    {"he", "Hebrew"},
    {"he-IL", "Hebrew - Israel"},
    {"hi", "Hindi"},
    {"hi-IN", "Hindi - India"},
    {"hr", "Croatian"},
    {"hr-HR", "Croatian - Croatia"},
    {"hu", "Hungarian"},
    {"hu-HU", "Hungarian - Hungary"},
    {"hy", "Armenian"},
    {"hy-AM", "Armenian - Armenia"},
    {"id", "Indonesian"},
    {"id-ID", "Indonesian - Indonesia"},
    {"is", "Icelandic"},
    {"is-IS", "Icelandic - Iceland"},
    {"it", "Italian"},
    {"it-CH", "Italian - Switzerland"},
    {"it-IT", "Italian - Italy"},
    {"ja", "Japanese"},
    {"ja-JP", "Japanese - Japan"},
    {"ka", "Georgian"},
    {"ka-GE", "Georgian - Georgia"},
    {"kk", "Kazakh"},
    {"kk-KZ", "Kazakh - Kazakhstan"},
    {"kn", "Kannada"},
    {"kn-IN", "Kannada - India"},
    {"ko", "Korean"},
    {"kok", "Konkani"},
    {"kok-IN", "Konkani - India"},
    {"ko-KR", "Korean - Korea"},
    {"ky", "Kyrgyz"},
    {"ky-KZ", "Kyrgyz - Kazakhstan"},
    {"lt", "Lithuanian"},
    {"Lt-az", "Azeri (Latin)"},
    {"Lt-az-AZ", "Azeri (Latin) - Azerbaijan"},
    {"lt-LT", "Lithuanian - Lithuania"},
    {"Lt-sr", "Serbian (Latin)"},
    {"Lt-sr-SP", "Serbian (Latin) - Serbia"},
    {"Lt-uz", "Uzbek (Latin)"},
    {"Lt-uz-UZ", "Uzbek (Latin) - Uzbekistan"},
    {"lv", "Latvian"},
    {"lv-LV", "Latvian - Latvia"},
    {"mk", "Macedonian (FYROM)"},
    {"mk-MK", "Macedonian (FYROM)"},
    {"mn", "Mongolian"},
    {"mn-MN", "Mongolian - Mongolia"},
    {"mr", "Marathi"},
    {"mr-IN", "Marathi - India"},
    {"ms", "Malay"},
    {"ms-BN", "Malay - Brunei"},
    {"ms-MY", "Malay - Malaysia"},
    {"nb", "Norwegian (Bokmål)"},
    {"nb-NO", "Norwegian (Bokmål) - Norway"},
    {"nl", "Dutch"},
    {"nl-BE", "Dutch - Belgium"},
    {"nl-NL", "Dutch - The Netherlands"},
    {"nn", "Norwegian (Nynorsk)"},
    {"nn-NO", "Norwegian (Nynorsk) - Norway"},
    {"pa", "Punjabi"},
    {"pa-IN", "Punjabi - India"},
    {"pl", "Polish"},
    {"pl-PL", "Polish - Poland"},
    {"pt", "Portuguese"},
    {"pt-BR", "Portuguese - Brazil"},
    {"pt-PT", "Portuguese - Portugal"},
    {"ro", "Romanian"},
    {"ro-RO", "Romanian - Romania"},
    {"ru", "Russian"},
    {"ru-RU", "Russian - Russia"},
    {"sa", "Sanskrit"},
    {"sa-IN", "Sanskrit - India"},
    {"sk", "Slovak"},
    {"sk-SK", "Slovak - Slovakia"},
    {"sl", "Slovenian"},
    {"sl-SI", "Slovenian - Slovenia"},
    {"sq", "Albanian"},
    {"sq-AL", "Albanian - Albania"},
    {"sv", "Swedish"},
    {"sv-FI", "Swedish - Finland"},
    {"sv-SE", "Swedish - Sweden"},
    {"sw", "Swahili"},
    {"sw-KE", "Swahili - Kenya"},
    {"syr", "Syriac"},
    {"syr-SY", "Syriac - Syria"},
    {"ta", "Tamil"},
    {"ta-IN", "Tamil - India"},
    {"te", "Telugu"},
    {"te-IN", "Telugu - India"},
    {"th", "Thai"},
    {"th-TH", "Thai - Thailand"},
    {"tr", "Turkish"},
    {"tr-TR", "Turkish - Turkey"},
    {"tt", "Tatar"},
    {"tt-RU", "Tatar - Russia"},
    {"uk", "Ukrainian"},
    {"uk-UA", "Ukrainian - Ukraine"},
    {"ur", "Urdu"},
    {"ur-PK", "Urdu - Pakistan"},
    {"vi", "Vietnamese"},
    {"vi-VN", "Vietnamese - Vietnam"},
    {"zh", "Chinese"},
    {"zh-CHS", "Chinese (Simplified)"},
    {"zh-CHT", "Chinese (Traditional)"},
    {"zh-CN", "Chinese - China"},
    {"zh-HK", "Chinese - Hong Kong SAR"},
    {"zh-MO", "Chinese - Macau SAR"},
    {"zh-SG", "Chinese - Singapore"},
    {"zh-TW", "Chinese - Taiwan"}
};

I created this since .net core does not include CultureInfo.GetCultures!