Fetch redirects at build-time from the Redirection plugin in WordPress, taken from JonnyTurbo in the Headless WP Discord - https://discord.com/channels/836253505944813629/836658991253553172/1012026516718223492

fetchWordPressRedirects.js

async function fetchWordPressRedirects() {
    if(!process.env.WORDPRESS_USERNAME
    || !process.env.WORDPRESS_PASSWORD
    || !process.env.REDIRECTION_API_ENDPOINT) {
        return [];
    }

    const base64UsernamePasswordToken = Buffer.from(
        process.env.WORDPRESS_USERNAME + ':' + process.env.WORDPRESS_PASSWORD
    ).toString('base64');

    const resp = await fetch(process.env.REDIRECTION_API_ENDPOINT, {
        headers: {
            Authorization: `Basic ${base64UsernamePasswordToken}`
        }
    });
    const data = await resp.json();

    if(!Array.isArray(data.items)) {
        return [];
    }

    return data.items
        .filter((redirection) => redirection.action_type === 'url')
        .map((redirection) => ({
            source: redirection.url,
            destination: redirection.action_data.url,
            permanent: redirection.action_code === 301
        }));
}

next.config.js

module.exports = {
  async redirects() {
    const wordPressRedirects = await fetchWordPressRedirects();
    return wordPressRedirects;
  },
}