Your experience mirrors one of my friends almost exactly. Age, heavy O2, and everything. He has refused to get the vaccine after his hospitalization, depending completely on his natural immunity from having had covid. Except he is now eight months post-hospital. Still on oxygen, still unable to take more than a few steps without having to stop and rest and huff and puff to bring his O2 sat back up out of the low 80's. He is a slave to his pulse ox. Stairs are out. As is any place without hand holds to keep him upright while "wall walking". He needs places to rest every few feet, and friends to carry his things. He can't make it from the handicapped parking space to the door of the store, let alone go inside and walk around shopping. His life is reduced to sitting in a chair now. The 15 foot trek to the bathroom just about takes him down. I have no idea how he makes it to his bed at night - that has got to be at least 30 feet. Him moving from chair to chair is about as tough as one of us climbing Mt. Everest. I can't imagine he could live through another bout with covid, or much any sickness for that matter, but the decision to refuse vaccination is his to make.
I hope your outcome is better than my friends. And that you might consider some additional protection to make sure you don't have to go through this sickness again.