Of course you can, fat (not weight) only comes back one way, the actions you take.
No, it’s not a sliding scale of progress in any of those. Just being in ketosis is the goal, the levels are meaningless with the exception of people doing keto as a medical intervention. Loss of appetite isn’t a positive, loss of (excessive) appetite because of sugar it fine and normal, but otherwise it’s a sign of metabolic slowdown, which will tank your goals real fast, and make regain very easy.
Take measurements, use your eyes, see how clothes fit, you can go all the way to DEXA scans, which is what I do, but the scale weight alone isn’t telling you how you’re progressing (or failing). At my heaviest I was 300, at my lowest during everything the high 180’s, I’m not 210lbs and less fat on me than when I was in the 180’s. The scale is only one piece of it. Pay attention to it, but take it in correct context.