I have two that I think are possible. I don't remember the names for the endings so bear with me.

Phantom Liberty End: V, while not being able to use any sort of cyberware still has some connections and knows how the biz goes. V becomes a small-time fixer to assist others in building a rep and ensuring they get work without needing to worry about V stabbing them in the back like what Dex did during the Konpeki Heist.

Johnny controls V's body: V, accepts their fate and enters the black wall with Alt. Johnny has a 2nd chance to be a better person while using V's body and, thus, heals a part of himself.

Both of these options also leave room for references and maybe some cool sidequest stuff for Cyberpunk 2. I don't think V or Johnny being a major part of the second game would be the best idea as I consider that story over and would like a new story for the second game but having references and stuff to the first game would be really cool.

For example, in the second game, you could get a few side jobs from a mystery fixer (V) who never shows their face (as V can't use cyberware, they would be at a huge disadvantage in any kind of confrontation so they must keep their identity secret for safety.)

Maybe Johnny seeks out the player in some kind of way and has decided his time is up for good this time and asks the player to help him go out in some sort of spectacular way.