Walking, with or without a walker can certainly be exercise......or not, depending on what you actually do. If you're walking for exercise, you want to start off slowly, because your goal is to increase you endurance, not your speed or the distance you can walk, just time. You want to keep moving without stopping for as long as possible.

Your first target is 30 minutes, and very few of us can do that when we start. So we start very slowly and go as long as we can before we have to stop for breath. Start doing PLB when you start walking, and that will keep you going longer before you have to stop and catch your breath. Pay attention to the time, so you know how long you actually walked. Rest and then do it again, for the same amount of time until you've done 30 minutes total. Then do the same thing the next day and the next. After four or five days, add 30 second to a minute to your time before you stop. Keep building on that until you can do 30 minutes. The you can add speed, time or distance. You want to walk for at least 30 minutes daily.

You also need to work with weights/resistance for the upper, lower and core muscle groups. Usually three times a week to plenty for weights, and you should do about 30 minutes each time.

I was given a walker after a 40 day stay in the hospital and rehab in 2015..
I have not had to use it for several years as I can walk well with out it, but I do use it when I walk the walking path in the mornings as my balance goes off on a long walk. I just walk straight ahead and after awhile I drift from right to left,, the walker keeps me where I should be.
It is considered exercise if you use it to walk . I walk 2 miles with it, has a seat if I need it but never do as there are benches scattered along the walking path.I
keep my water in the basket under the seat, a small box of tissues and my cell phone.

I use it to haul my groceries bags from the car to the kitchen, Just put them on the seat and hang some off the lighter ones off the handles .

Housework is considered exercise now too . Just keep moving and do what you can . Rest if you need it .
Have a great breathe easy day . BTW when I started walking I could barely make 2 blocks each way . I just pushed a little farther ever few days .

If I have to walk more then a few feet i use my walker I also found that if i use a cart at jthe store I can breathe better so the walker is very helpful i find that carrying my oxygen and purse makes it so much harder to breathe so i put them on the walker and it is so much better so to answer your question yes a walker will help you to breath while walking hope this helps

I couldn't walk very far without my walker.bedt thing ever

Any exercise is better than none. You are still walking with a walker but you have the security of knowing you can sit down if you need to. I use oxygen and am going to get a walker with a seat and wheels (rollator) so I can put my purse and oxygen down on the seat and us all my muscle power to walk.