@l @sjw @p @Moon yeah activitypub isn't quite friendly when it comes to sharing posts

you could limit it to post made in the last week, or a set number for each user just to get a taste
your instance will accrue tons of posts either way

but the idea of backfilling them on demand is a bit more complicated
as there's no mastoapi for it, and pleroma-fe would not know of it
you could probably hack with with a *monkey user javacript
but that's outside of my knowledge