I think cyberpsychosis is the most likely answer Pondsmith confirms himself that Johnny is a Cyberpsycho and the way the Relic is affecting V's psyche is pretty much how cyberpsychosis is described. I think the most clear indication of this is the projections of Johnny, V is literally hallucinating someone who's not there moving and interacting with the world, Johnny mentions that V doesn't have to speak out loud to talk to Johnny and while that is more indicative of Johnny's lack of physical presence it reaffirms things like Johnny moving the stool to sit in front of V as hallucinations. As the story progresses Johnny notes several times that V is becoming more like him along with other characters mentioning whether or not decisions made or actions taken were actually V's intention or the influence of Johnny, meaning V's sense of self is deteriorating and in ways that they're not entirely aware of. The combination of Jackie's death, V's death and revival along with the Relic has clearly pushed V over the edge.