some of the privacy messengers here (like Briar) have blogging/forum features
many people incorrectly assume briar aims to provide some sort of anonymity, because it uses tor onion services and is a self-described "secure messenger". however, that is not the case:
https://code.briarproject.org/briar/briar/-/wikis/FAQ#does-briar-provide-anonymity (answer: no)
tldr: briar contacts, even when only actually using onions, exchange their bluetoooth MAC addresses and their most recent IPv6 link-local address and last five IPv4 addresses briar has seen bound to their wlan interfaces, just in case you're ever physically near a contact and want to automatically connect to them locally.