@nuxtjs/i18n takes advantage of Vue I18n ability to handle localization fallback. It is possible to define a single fallback locale, an array of locales, or a decision map for more specific needs.
nuxt.config.js
export default defineNuxtConfig({ // ... i18n: { vueI18n: { fallbackLocale: 'en', // or fallbackLocale: ['en', 'fr'], // or fallbackLocale: { 'de-CH': ['fr', 'it'], 'zh-Hant': ['zh-Hans'], 'es-CL': ['es-AR'], 'es': ['en-GB'], 'pt': ['es-AR'], 'default': ['en', 'da'] } } }, // ...})More information in Vue I18n documentation