This app receives event sent from Mastodon's WebPush REST API, then this app send it to my mobile app (Subway Tooter) via Firebase Cloud Messaging.
- Mastodon's WebPush REST API https://github.com/tootsuite/mastodon/pull/7445
- Subway Tooter https://github.com/tateisu/SubwayTooter
Currently payload decryption is not implemented because Subway Tooter does not requires it's content, just use event as notification check trigger.
But if you want sample of payload decryption. see also
JWT verify sample
VAPID for Web Push