A small area in front of the patio door has lightened but the other 500 square feet of the room remains dark and beautiful. I sure don’t want to sand and refinish the entire room. Is there a way to blend a dark recoat of a compatible product on top of the aluminum oxide urethane?
In front of the patio door seems like the perfect location for a dust mat or a small piece of carpeting.
Not really. Any stain applied over the existing finish will obscure the grain, being semi-opaque. That will be noticeable.
Worse, you won't likely get a good sheen match. That means that while your color may be back, under interior lighting you'll see a marked difference in reflectivity.