One could probably use matrix (perhaps might need account creation?) or session or simplex (their accounts are sort of like addresses, easy to make compartively to matrix)

I have built dead simple bots on both session/simplex trying both of them out and session was the more ergonomic one to build on but simplex is more decentralized considering session's more crypto related and wants to ask you for money for node whereas simplex doesn't

Although on the other hand, simplex wants to do client side verification on their official client and their bot creation was really painful to start with so but I do feel like its more decentralized but not sure, Both have consequences but honestly I just really end up shilling signal in the end for most people's usual use cases which is communication but its super great to know that there are alternatives.

Matrix is really cool as well. especially cinny's ui (https://cinny.in)