I mean... I'll pass. Sorry.
Here's a very unique approach for a topic-based client. It also showcases that you can build anything on top of Nostr:
It utilizes nostr lists to save the topics a user has followed.
When a user follows a topic like #cordcutters, it utilizes rsslay.nostr.moe to create a Nostr profile. This profile is generated from the RSS feed of the corresponding subreddit (/r/cordcutters) and includes the #cordcutters hashtag in every post.
Here's an example Nostr profile: nostr:npub123xykft0hzerzpc7chwnqcgpsjl0ws2xs6zrkuyrpgnclgey5a7s2052xp.
Client website: https://agorasocial.app
It is developed by nostr:npub1k979np6dcpwh7mkfwk7wq3msezml48fh7wksp9hakakf8pwk3y5qhdz7te
Discussion
It's completely built around Nostr, with access to all the 'native' Nostr feed, as well as zaps and an excellent thread design. It's a fully working nostr client which some advance features.