// @filename: pages/[lang]/about/index.js
import { useRouter } from "next/router"
export async function getStaticPaths() {
    return {
        paths: [
            {
                params: {
                    lang: 'en',
                },
            },
            {
                params: {
                    lang: 'fr',
                },
            },
        ],
        fallback: true,
    }
}

export async function getStaticProps() {
    const messages = {
        'en': "Good Morning !",
        "fr": "Bonjour!"
    }
    return { props: { messages } }
}

export default function Page({ messages }) {
    const router = useRouter()
    console.log(router.query)
    console.log(messages)
    return <div style={{
        fontSize:
            "40px"
    }}>{messages[router.query['lang']]}</div>
} 

how can I migrate such a page from pages router to app router guys, @Multiflora rose seed chalcid @Silver Marten

With keeping the page statically generated