Telegram allows you to "unsend" messages coming from either party, and has no time limit

They’re not the biggest messaging service that says that.

But yeah, this is a selling point, and should be a selling point for more things.

I don’t really approve of “ephemeral messaging” as a privacy feature, though. If people were to get the impression that such a thing were physically possible – which it is not – that misinformation is a security issue in itself.