My Mom, who had asthma, COPD, bronchiectasis, heart failure and arthritis and had a stroke had a technique that worked for her. First of all, early on she used a cane, later a walker. She would walk until she felt quite short of breath, lean on the cane or walker to rest, then decide whether to walk a little farther, or to turn for home (this was in the halls of her building in latter days.) She tried to do it 3 times a day. She managed to VERY slowly build her ability to walk, until she could go 2 full blocks.
I used the same technique when recuperating from severe pneumonia in 2018. My first walk was only to the mailbox and back - 100 feet total. Within a few months I could walk a mile on a good day.
You might not get as much progress with your COPD, but a little at a time I bet you would see progress. By challenging your lungs, you might be surprised
Sue
PS - I always have my rescue inhaler in my pocket when I walk.

Have you tried pursed-lip breathing? It's awkward at first but after a while, you learn to get deep breaths into the lower part of your lung (s), hence more O2 to breathe easier.https://www.lung.org/lung-health-diseases/lung-disease-lookup/copd/patient-resources-and-videos/pursed-lip-breathing-video. It made a big difference to me.