I haven't looked into them, but I would presume you could write a decent scraper for most of the content.
Discussion
But user is not going to manually publish it? And if they did, then what - it gets published at once and floods the network?
I suppose you could create a tool for users to run a script and import their notes.
We’d need a way to not flood the protocol though.
I think that tool exists already, if I'm not mistaken. On highlighter.com, there's the possibility to import any blog post as a nip-23 long-form note.
Oh!
A wordpress/etc plugins make sense to me - create 'blog' profile, store keys in the plugin, export all content to long-form (existing & new as published), notify in admin area about kind-1 comments etc.
Flood isn't a problem, at least for now - the load will be trivial, and you could set created_at timestamp as old as you like (to match the dates on old posts). The issue is that most relays won't accept old events atm, so this would require some (paid?) arrangements with relays.