Hi Haui,
just my perspective regarding mirroring reddit subs to the fediverse. I personally don’t like those posts since they mostly don’t create any activity here and most of the time there isn’t even any response by the post creator over here.
In addition every sub, post and comment created on reddit is owned by reddit since the user transfers all it’s copyright to reddit. That may cause trouble in the future.
That said here is a bot that can do that afaik, it can a least crosspost new content.
do not microwave