Molly has a bounty for replacing MobileCoin with Monero. They have worked on a Monero library.
For a messenger with wallet and sending to recipients I can only think of Keychat at the moment.
GitHub
GitHub - mollyim/monero-wallet-sdk: Kotlin library for integrating Monero wallets in mobile apps.
Kotlin library for integrating Monero wallets in mobile apps. - mollyim/monero-wallet-sdk
