Your first website doesn’t tell any ingredients, nor the way these drops are supposed to work. All they tell is that the composition is secret. They also tell that all anaerobic bacteria are killed by these drops – which is logical, because anaerobic bacteria are defined as those bacteria for which oxygen is toxic. They imply that it kills [all] bacteria, but that cannot be true.
Anyway, telling what it does and whether it is a scam, or even dangerous, is not possible because they provide no information whatsoever. You just have to trust this commercial company.
Your second website tells some lies. They talk about “the ever-decreasing percentage of oxygen in the air”. This is not true: the amount of oxygen in the air has not changed for the last several thousands of years, and it is not expected to change in the foreseeable future.
They continue to tell that oxygen is used to burn fat. They make it appear that just adding oxygen to your body will automagically burn fat. This, of course, is pure nonsense.
Next, they tell that their drops increase the pH of the body. If this would be true, the body would very, very quickly undo any change in its pH.
I wouldn’t trust any seller who makes such unjustified, even downright false, claims.
Your third website is the only one that is open about what they sell: sodium chlorite. Sodium chlorite is a chemical compound used in the production of paper. It does contain oxygen, so that part of their claim is true.
However, their website contains some nonsense. Like the part where they state that “Stomach acid makes the atoms in food break apart and become new atoms.” Breaking atoms apart and make them become new atoms? That only occurs in nuclear reactions! Things like that certainly do NOT happen in your stomach, thank goodness!
The next nonsensical part is the phrase that “Contrary to the FDA claims they don’t, cells do need oxygen”. They really make it appear like the FDA says that cells do not need oxygen – what nonsense! The only purpose of this phrase is to give them an excuse to attack the FDA, because everyone knows that cells DO need oxygen. (Including the FDA, but this site falsely claims otherwise.)
Anyway, sodium chlorite is used to decontaminate food and surfaces. It is toxic. Therefore, the maximum amount of sodium chlorite contamination that is allowed in drinking water is set to 1 milligram per liter.