Hi , and welcome! I see you are a new member here, having joined early this morning earlier today. You may be aware that we cannot provide medical advice or diagnostics over the internet (for your own safety), but your concern certainly warrants a reply.
I see our good member, , has already joined in the conversation and provided her own special brand of support.
I concur with her suggestion, too! Going 'by the book', your nighttime oxygen saturation level (as recorded on your Apple watch), would be considered to be somewhat low. As dltld said, each patient with COPD is different - my comment assessing percentages, is 'by the book'. The most prudent action for you to take next would be to report your circumstances to your own private medical doctor (PMD). The physician will be able to guide you in this regard.
Please do check back and let us know how this all turns out for you.
Good luck!
Leon L (author/moderator)