wish i could see what this reply was in reference to but since im tagged i will chime in that it sounds like you dont want messages to 'leak or be tied to your main nostr identity'.. so, use or build tools that take advantage of AUTH, multiple keys+single session, a relay you are in control of, and nip70 sprinkled on top.

relay.tools can set these types of settings, but its mostly proof of concept for anyone wanting to head down this path (thats what the "turn on anon posting button is for).