This tool, then kind3.xyz and listr.lol should really be all together on a single site.
yeah, pretty much just let the user define it; i.e. I wouldn't want to unfollow nostr:npub1sn0wdenkukak0d9dfczzeacvhkrgz92ak56egt7vdgzn8pv2wfqqhrjdv9
Discussion
Yes, you would need a way to whitelist certain npubs. The idea is very similar to Untweeps, where are you can set a time threshold for accounts to unfollow. https://untweeps.com