There's different kinds of DVMs. The ones we see in Gigis screenshot are content discovery DVMs. They aggregate notes and apply a set of rules or filters on the notes and build a feed based on these rules. There's topic related ones, follow related ones, most zapped, most engagement in various timespans on various relays and for different kinds. This is a growing open marketplace and every client that implements nip90 can benefit from it. There might be free or paid or subscription based ones, but currently most are free to use.