Is there an private decentralized messaging app?

I'm wondering if there is an app as secure as signal but that wouldn't rely on centralized servers? Where each device would act as a server when finding your contact's ip. That would totally be censor resistant and reliable. You could potentionally directly connect a device known to you that witholds other peer connections so you wouldn't need a server at all. Is there? Would it be possible? Would it be reasonable?

app decentralized messaging messaging app privacy