It has to be fast paced with voice calls/phones because it has to tell a story in the fastest way possible (within 11 minutes with most of or all of the kids presumably entering the medium and showing their new lands at the very end) because the supposed recorded attention span of younger generations is supposedly the lowest it's ever been. Karkat and the trolls will probably be calling form various "unknown numbers" via the meteor providing infinite anonymous burner phones like how it provides infinite "shitty coffee" as seen when Dave meets Kanaya and Rose in that lab room. The kids will recognize it's the trolls by their voices with the troll reveal to the kids being in the full show at some point if the pilot gets enough views. Karkat will turn on the his video and be like okay fine I guess you can see what we look like since you've earned my trust. idk something like that maybe idk. Obviously WE the audience get the troll reveal by the end of the pilot though.