https://youtu.be/Q5zbDrcBFXs?si=3w7OxQuZjJwpCm3I
Hopefully it was explained to You that the CO2 in our body is mostly in our blood stream, not in the lungs. A high CO2 buildup throws off the pH balance which sets the stage for an Exacerbation (or ER visit).

Supplematal Oxygen does helps prevent damage when the gas exchange is lower the lungs (like during an infection). It takes some getting used to, indeed. Other helpful DAILY activities would include active breathing techniques (like Pursed Lips) and staying hydrated. VERY hydrated. Here is a longer discussion by someone smarter than me:
be Well.

Thanks for sending me this information as I do the pursed breathing but not daily but now I understand that I really need to as my avolia are full of bullea and 13 years ago I had a few removed that were very large and loss the lower lobe of my rt lung so it makes sense now for me to do pursed breathing exercises on a regular daily basis which calms my anxiety down having this explanation of what exactly CO2 retainer is ! I really appreciate your help! :)