I am using Molly on Android.

Then we should push Molly to look into LN, ecash or Monero support. Besides that I don't think messengers and wallets should be combined. It's just another lazy convenient thing that breeds future problems.

For real, I'm not sure what's wrong with just sending someone a wallet address and having them paste it into their wallet app of choice?

Molly has a bounty for replacing MobileCoin with Monero. They have worked on a Monero library.

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

For a messenger with wallet and sending to recipients I can only think of Keychat at the moment.

Because most people don't have any wallet. The idea is to give a wallet to every Signal user, to help (force?) adoption.

It looks like shit. Terrible UI that normies will never ever use.