Walking is great for maintaining base aerobic and leg strength fitness while recovering when we can't ride. Especially if you can develop a gliding, low-impact speed-walking form.
Back in 2018 after I was hit by a car, I was unable to ride outdoors for several months. And coincidentally I developed thyroid cancer the same year, so my energy level was in the dumpster.
A friend gave me his old Cyclops trainer, so a month after the injury I'd set up my old school steel road bike with a more padded saddle, wore thicker padded shorts, raised the stem, and was able to sit more upright without discomfort to keep the legs spinning.
But I got bored with that and began walking around the neighborhood. It was a bit awkward with one arm in a sling. And I was surprised to discovered my hips ached after only a couple of miles. Full body imaging scans showed no skeletal or joint problems below my back so I figured it was just unused muscles rebelling at new exercise. I kept at it and now I often walk, jog and run 3-8 miles several times a week.
At first I studied some YouTube videos on speed walking and easy jogging to ensure my form was good with minimal impact. And I got a couple of pairs of Under Armour Hovr Sonic shoes with a Bluetooth sensor in one shoe that synced with Map My Walk and Map My Run apps for realtime feedback on my walking/jogging form: cadence, stride length, etc. Really helped keep my form in shape to avoid injury. Not all UA shoes include that Bluetooth sensor, but the inclusion is less expensive than buying a separate tie-on sensor used by some serious runners. The Hovr Sonic and other UA Hovr shoes are still available online, usually heavily discounted for the outdated models that still work perfectly well.
I still have chronic neck pain from being hit by cars twice in 20 years, with a cervical spine ablation procedure coming up soon. The pain limits my time on the bike, so I've been doing a lot more walking and running the past couple of years. In many ways I still prefer cycling, but the great thing about walking and running is the less elaborate gear and prep, compared with "serious" road cycling. Some days I just go out wearing the same shorts and t-shirt I wore to sleep. My prep time for a road bike ride can take 30 minutes to check everything. For walking and running, maybe 5 minutes at most.