It seems concerning that you can’t do pull-ups if you’ve been lifting for a few years and done the V-Diet twice. That combination seems like it would put you in a good position, but not sure your height / weight.
My personal advice from having been in a similar position (could only do 1 pull up) is to really focus on them. Do sets of 1 until you get 10 and so on. Aim for a total of 30 reps and get there any way you can each back session. I would also throw them in on off days for extra emphasis. I would set an end goal of 3 sets of 10 reps before adding any extra weight.
That being said, doing the “pull-up” where you lay on the ground in a squat rack and set up the bar at a comfortable level to pull your upper body up seems like the way to go, or just the traditional lat-pull down. If you truly can’t do a pull-up, I would do the heaviest possible lat-pull down you can do and train it similar to a heavy bench press (heavy, low reps) until you’re doing a lat-pull down of your body weight for 1 set of 10 reps at least. Once you can do that, you should be able to do at least a couple pull ups and go on from there.