Under marked otherwise, all posts from this account are #CC #BYSA 4.0. Unless I send a DM, I want all my posts publicly visible, to any web browser, and any other user app or archival/ research system that speaks #ActivityPub (and ideally #Diaspora and #Zot too). I'm happy for them to be indexed by any search system and included in any relevant search. That's why I publish them on the web with Mastodon. When I want to have private discussion, I use DMs. One day the AP-verse will do this better.
There are different approaches to private social messaging, even within the fediverse. Diaspora was one of the earlier examples, allowing users to give access permission to only one person (like a #DM), some people (like group DMs), a group of people defined by the posting user ("aspects"), or everyone (public). #Friendica does private messages with #DFRN and Dispora, and maybe now AP? Hubzilla and now Zap have been doing federation of private content with Zot, later AP. Consensus is emerging.
> Would be good to pull more of a focus on private social messaging apps? To work kinda like Mastodon? But any length message.
All the apps I mentioned in the post you're replying to fit that description.
* Diaspora: supports image uploads, not documents, like Mastodon
* Friendica: supports image and file uploads
* Hubzilla: supports photo albums and file uploads
* Zap: haven't tested yet, but it's a fork of Hubzilla, so ...
The social network of the future: No ads, no corporate surveillance, ethical design, and decentralization! Own your data with Mastodon!