The reason you get 02 prescribed is that you don't get enough 02 from room air to ensure that all the parts of your body get enough 02 to function correctly. When you don't have enough 02 your body sends what's available to the major organs: heart, brain, etc. Other organs just do without and that leads to organ failure. 02 is not designed to help your breathing; it might, but that's not the point. The point is to make sure that your body gets all the 02 necessary for everything to work properly. Lung disease makes changes to your lungs that mean that they can't provide 02 to all the necessary parts of the body and the supplemental 02 provides that. So 02 is therapy for lung disease.

https://youtu.be/MD1SOOlFw4c
The oxygen balance in the blood is controlled by many things. Not just breathing. We focus on respiratory and circulation issues because that is the arena we are fighting in.
But diet, hydration, hormones and many other things come into play. Here is one quick video talking about how pH and vitamins affect Oxygen in the body.
When they come take your blood labs and hang an IV bag everyday in the hospital, It is for this reason. Carbon dioxide can take over where Oxygen should go and makes the blood more acidic. Water is one key thing to restore the balance. It is an ever moving target, indeed.
Be well

Thank you so much for sharing this with me

Thank you for your response.