toniniyo Cache invalidation is very tricky. You cannot remotely control cache of a PWA application but we have Force Clear Cache option that will force update the PWA on all user phone and fetch new settings. (But if the customer have open multiple tabs of your PWA on chrome, this won't work - this is a PWA limitation)
Also, the customer need to be registered and only when they goto homepage (stores listing page) they will be shown the push notification popup.
Important: if you have changed the server key, web certificate and Id of the push notification, then you need to login to your server DB (phpmyadmin) and delete everything present in the push_tokens table as those push_tokens are of no use.
After deleting new push notification subscribers will be added there and they will receive push notifications.
