I know you’re a Piefed developer, so you probably know what’s possible and what’s not better than me. But honestly, the encryption part makes me think you probably want a new protocol designed with that in mind from the start. In my opinion, it’s too destructive for compatibility with other ActivityPub software and instances running older versions of them especially.
Combating spam despite the simplified account creation will probably require the implementation of something like Reddit’s karma system. Which isn’t a very popular idea I think.
Regarding the ephemeral content… please don’t. It might sound cool on paper, but it just adds FOMO. We shouldn’t promote doomscrolling and brainrot with the addition of features which require you to quickly scroll through shit to not miss out on posts that disappear after a timer has passed.
They do have a dedicated “Crawler” page.
And they do mention there that they use a website crawler for their Developer Tools and Network features.