As someone who has actually tried every healthy trendy diet you can possibly think of and has tried every sort of exercise imaginable, I can tell you that none of it has made me remotely better. I have also been taking all the classic gut supplements such as probiotics, as well as amino acid supplements and don't even get me started on vitamins. Also I hate to turn this into a humble brag, but I have had a personal trainer and all the jazz to try and help. I actually did manage to push my body pretty far, by for example benching my own body weight and being able to sumo deadlift twice my bodyweight. But that did not help my CFS in any way in other areas of my life. If anything it just made it worse. And after doing exercise that would make my body struggle and sweat properly, I would always wake up the morning after with the flu / hangover, and I would not be able to focus for the entire rest of the day. And now I have not exercised for a year because my body has become so f***ed by CFS. Sure I can still ride my bike places, but I go at snail speed. Also my brain-fog has become so bad that I had to end my studies. So can't exactly say exercise and a healthy lifestyle was a success. I used to do AP math in high school, and now I have trouble doing multiplication in my head, and I can't read anything remotely complicated anymore.
I could honestly not tell the difference between a period where I would be eating fruits, veggies, coconut oil and meat all day or a period where I would just be sitting in my room eating Nutella with a spoon (ok I have never actually tired this, but you get the picture).
And yes, I have also done absurd things like yoga breathing exercises every day as well as using a neti-pot. Never sticking that blue elephant penis in my nose ever again. I have also tried meditation and listened to all sorts of relaxing music, guided meditations, or nature sounds you name it.
The thing is CFS probably covers a lot of different ''diseases'' or whatever you want to call it. So one could easily imagine a subgroup of CFS sufferers getting better with lifestyle changes, whereas others won't notice any effect at all. We like to believe that we are in control of our own destinies, and that we can therefore in some way take control our own lives, in this case by eating healthier or changing lifestyle. The truth is that most diseases just are not treatable with healthy food and or lifestyle changes.
That being said I would of course always advise leading a healthy lifestyle. But for me, I honestly can not tell any difference and I often feel like my energy is better spent elsewhere than preparing healthy meals, which can actually be quite draining to make, especially on crash days. Luckily healthy recipes with Onions and carrots are just routine on my good days now and therefore don't really take anything out of me.
Lastly I will be honest and say that I actually did believe a lot of the things I tried actually helped me out. I could easily imagine myself having made a Youtube video or reddit post about my ''success story'', with the intent of helping others. It is only with the benefit of hindsight that I realized that nothing worked, and the exercise might very well have made my condition the worst it has been in 9 years.