Doing RSS Import first might be easier than ActivityPub and help writers get content onto the site faster.
Cool, we're busy working on RSS importing now. Should be up in a day or two.
I wrote elsewhere that even if you don't do ActivityPub publishing, being able to import from the ActivityPub 'article' type would be a nice feature. I don't know if people have played with that kind of one-way AP integration much, but it'd be neat.