Currently, posters can be notified about replies to their posts or comments, or subscribe to a community for notifications about posts in that community.
It'd be good to be able to subscribe to a post or comment too.
This is a feature that as far as i know lemmy does not have, so it might be worth it to checkout and support piefed, it will probably be useful if there are certain topics that are really relevant to you and you want to develop in depth knowledge of.