I’d love to see that. Could you simulate iMessage?
Yes it’s possible, but it’s not something you can easily scale.
I had a similar project a few years back that used OSX automations and Shortcuts and Python to send a message everyday to a friend. It required you to be signed in to iMessage on your MacBook.
Than was a send operation, the reading of replies is not something I implemented, but I know there is a file somewhere that holds a history of your recent iMessages. So you would have to parse it on file update and that should give you the read operation so you can have a conversation.
Very doable in a few hours unless something dramatic changed with how the messages apps works within the last few years.
They are all in a SQLite db on your disk.
If you mean hook this into iMessage, I don't know. I'm willing to bet it's way harder though because Apple
If you are willing to use Apple Shortcuts on iOS it’s pretty easy to add something that will be trigged when a message is received and can call out to a service or even use SSH to do something with the contents, including replying