If you will use same way to implement i18n to next.js app with App Router (on next.js v13+), good to know:
The locale, locales, defaultLocales, domainLocales values have been removed because built-in i18n Next.js features are no longer necessary in the app directory.
Taken from Migrating Routing Hooks documentation.
Usefull links for implement i18n with App Router: