Ok, this might be a dumb question, but is it really technically possible in any way - even a convoluted one, like manually downloading HTML pages from Facebook? - to mass import posts from one’s Facebook into Mastodon or Friendica instead of painstakingly copying them one by one? I’ve got a 10+ year archive to port and it’s a daunting task to go through them…
You might be able to self-host WordPress if it is just a matter of importing. As WP is federated, you can, presumably cross-post it from there.