Your first paragraph is wrong. Full spectrum products have been legalized by the federal government. There is a tiny amount of THC allowable by federal law. Tiny.CBD Oil can be one of two general things. First, it can be just the oil without any effective THC. That version is legal almost everywhere. Second it can contain THC. That is legal as medical marijuana or in states where marijuana has been decriminalized.
The evidence for the non-THC oils, where they eliminated placebo effect (i.e. people fooling themselves), shows that it can reduce inflammation. It is surprisingly much more effective when rubbed on the skin. This is due to poor absorption when swallowed and also deterioration in the digestive process.
That's it. That is all it does without the THC component. For some people that might be enough to justify what is to me an outrageously overpriced fad product. I can afford CBD, but for my rebuilt knee it didn't do any more than daily icing and a compression sleeve.
On the other hand, reducing or eliminating simple sugars has a much more dramatic effect on reducing inflammation throughout the entire body. High sugar diets cause chronic inflammation. One prominent source of dietary sugar is sweetened drinks. Even orange juice has significant dietary sugar. Potatoes and other starchy foods do have sugars (carbohydrates), but these are complex sugars that don't have nearly as significant effects as simple sugars. Eliminate any foods with added sugar and your inflammation will go down. The side benefit is that all inflammation is reduced, including in key areas of the brain where inflammation contributes to chronic depression. Hunger cravings all almost disappear.
After surgery in 2016 I changed to a diet of basically meats and vegetables. The overall results were pretty amazing. The most significant change was a complete lack of craving for food or snacks. I still get hungary, but if I'm busy at work where I have to wait until 3 to eat lunch, I'm not feeling like I'm dying for food. It did more for my knee pain than $150/month powerful CBD oil (I was buying the strongest I could get).
Remember that the human mind can convince us of things working whether they actually do anything or not. A great example is any homeopathic product. They, by definition, do not contain any medicine or even any actual ingredients beyond water or (in pills) inert fillers. But people will swear they "work". Run a test where they receive tap water vs. 30C homeopathic product and there is absolutely no difference in results between the two study groups.
Actual studies show CBD (without THC) does work for one thing. It does reduce inflammation to a degree. But it is extremely expensive for what it actually does. If you can get CBD with THC legally, that is a different story.
At 58, with no testosterone replacement, this way of eating has kept me lean and muscular enough to be very happy with it.