No. Logging in to manage your wallet. It’s web based so there is no app to download. As for using it with nostr, you can receive zaps by adding your CoinOS lightning address in your nostr profile. To use it for sending zaps, copy the NWC string from your CoinOS settings and paste it into the correct place in your nostr client’s settings. I apologize I don’t have amethyst so I don’t know where the setting is.