There’s also the issue of bad people being reincarnated. Good people don’t have to worry about that since they just go to Heaven or hang out with the Kais. But bad people get assigned a sentence in Hell until they repent, at which point their soul gets cleansed and they get reincarnated as a completely new being, essentially being given a new chance to not be a bad person this time around.
Once a person has been reincarnated, they can’t be brought back to life because there’s no trace of them left in Otherworld to bring back. They’re alive again but as a new person with new memories. You could maybe wish for them to be given the memories of their old life, but if they were a bad person before then that’s likely not a good idea because it ruins the whole point of them being reincarnated.
They actually mentioned how Frieza was taking a lot longer to repent than most people do, which means the average person doesn’t stay in Hell for very long before they go through the reincarnation process. There simply might not even be any saiyans left in Otherworld to bring back to life if they’ve all reincarnated by now. Some might be humans, others might have been born as Namekians, and the rest might have been born as other aliens or maybe even animals.
This is what happened to Kid Buu actually, except they skipped over giving him a sentence in Hell. He was literally insane, with no mental capabilities. There wouldn’t have been any point in giving him a sentence in Hell because he wouldn’t even understand where he was at or why he was there. So Yemma just skipped straight to the reincarnation process for him.
But Goku requested specifically for Kid Buu to come back some day as a good person that he could fight again, so Yemma made the decision to reincarnate Kid Buu as a human on Earth to pay Goku back for saving the universe. Had Goku not made that request, Yemma likely would have reincarnated Kid Buu as something else.
So the dead U7 saiyans are most likely all alive again, having repented and gone through the process of reincarnation. They could be anyone, depending on how long they lasted in Hell before they repented. Pretty much anyone born after Planet Vegeta was destroyed is fair game to be a former saiyan. Dende could be one. Krillin’s daughter could be one. Even Gohan could be one since there’s no rule saying a saiyan can’t be reincarnated as another saiyan.