“We are already testing our multichain notifs on Polygon testnet. We are excited for a true multi-chain experience where a user, no matter what network they are on (Ethereum, Polygon or Solana), is able to receive communication from any other network where EPNS is deployed.”

https://www.theblockcrypto.com/linked/141943/ethereum-push-notification-service-raises-10-million-in-series-a-funding