Right now, there are no nostr microblogging focused clients that I know of that allow users to create their own custom feeds.

I've toyed with the idea of this in my mind. People want to be able to have a feed of certain tags, of a certain relay, of a certain subset of their follows, of certain kinds, or any combination of these. Right now, all anyone can see is their follows list kind 1, 6, 16 and 30023.

There is no nip for a feeds kind of this sort, so something like this would be stored locally unless a nip is created. I'd be willing to help specify an event kind that stores a custom feed if there were interest in implementing this.