On: I built an iMessage bot using Beeper

[apetresc]

That option exists today. The iMessage bridge needs to run on a Mac, for obvious reasons, but not only can you self-host it, but you can plug your self-hosted bridge into the public homeserver/client entirely through their settings panel.

Here is the bridge repo: https://github.com/mautrix/imessage (tulir is employed by Beeper)