I don't agree with isolating on specific theme relays. Most people just use the default relays their client provides, but also it provides those specific relays with power, which goes against the principles behind Nostr.

If the largest Politics relay suddenly decides to ban people with a certain view, then that is real power they have since they control the largest Politics community.

The nip72 extension with community exclusive posts is better than topical relays because posts can be anywhere. I intent to create topics within each user. You can subscribe to the user OR to a community or that user: Vitor General or Vitor/Android. This allows technical discussions in communities and general posts in the main feed.