Does this exist: Truly anonymous content sharing platform or social network?

Given the extistence of technologies like Monero and SimpleX chat, I wonder if it is possible for a truly anonymous content sharing platform to exist? And does it?

Use cases:

• sharing pirated content without a link back to you
• journalists or political activists not wanting to be found or caught by a government

The platform should not allow the following to know the details of what you do on this platform:

• users on the platform: should not know the identity of a poster unless they disclose it
• the host of the platform: should not know which content belongs to who, or be able to deduce it via traffic logs
• Intermediates like the ISP, DNS, or your router should not be able to link any content to you. However it is okay if they know that you use the platform at all, just not what you do with it.

Does something like this exist?