DEMO: https://nuxt3-ssr-firebase.web.app/
create .env file with content below and update your firebase configuration
GOOGLE_APPLICATION_CREDENTIALS must be the single line of the service account file content Admin-SDK
FIREBASE_API_KEY=...
FIREBASE_AUTH_DOMAIN=...
FIREBASE_PROJECT_ID=....
FIREBASE_STORAGE_BUCKET=...
FIREBASE_MESSAGING_SENDER_ID=...
FIREBASE_APP_ID=...
FIREBASE_MEASUREMENT_ID=...
GOOGLE_APPLICATION_CREDENTIALS='{"type":"service_account","project_id":"***","private_key_id":"***","client_email":"f***","client_id":"***","auth_uri":"***","token_uri":"***","auth_provider_x509_cert_url":"***","client_x509_cert_url":"***","universe_domain":"***"}'
WEBSITE_URL=....