I just whipped up a super hacky Python 2 script which will notify you if someone replies to your comment, without requiring your email, and can be self hosted (fill in your HN username in the variable):
https://gist.github.com/Decagon/1ef31011d05bf71aa5570f2bddda...Just run it with: while true; do python HNgetCommentReplies.py | mail -s "new hn reply" me@example.com; sleep 1m; done;
(e.g. check every minute for new comment replies and mail output.) It will output "Reply to comment: hn-url" if there is a reply, otherwise it will output nothing. Unfortunately it doesn't save any state, so it doesn't know if it already emailed you a reply. This can be easily fixed but I don't have too much time right now. Also, it makes one query at a time, which is a bit slow (as it takes around 20 seconds to check for replies.) This can be parallelized to make it much faster.
Benefits of this script is that if it were centralized, n users could be subscribed to get notifications (e.g. a million users) it would only use one query to the hacker news server every 30 seconds or so. It just looks to see if all recent comments have a parent whose name matches yours.
I'll dogfood it for a while and see if any replies to this comment works.