Yeah for Usenet I use gnus, which keeps track of which posts I have already seen. It doesn't have notifications and I don't miss them, as long as I can see right away where the new posts are. I don't know what reshares are. Gnus does have a way to ignore specific posters or topics and I do use that. Every time I mull the idea of writing another forum poster, I come back to the realization that Usenet already does everything needed (at least on the backend), and has done so since the 1980s. A better NNTP to web gateway is all it could really use, for those who want to read with browsers.

For reply notifications, I use HN user ‘dangrossman’s HN Replies:

https://news.ycombinator.com/user?id=dangrossman

Show HN: HN Replies – Get notified of replies to your comments - https://news.ycombinator.com/item?id=11080539 - February 11 2016 (124 comments)

https://www.hnreplies.com/