Hello valpuia.
Partially it is fixed. You can use topic and Legacy Server Key from the admin panel.
For rest of the credentials, you can add the to code for now.
Files:
1. push-notification.js
location: PWA/src/Resources/assets/js/plugins/push-notification.js
Line: 5
2. service worker.js
location: PWA/publishable/pwa/service-worker.js
Line: 201-207, 212.
Than run "php artisan vendor:publish --force". This will publish your assets to public folder. That's it.