Office/desk work is better than WFH for getting movement in. A basic stuck at desk all day sort of day would be no less than 4k steps for me - WFH ~0 steps.
The number of steps is only a small part of the equation, sustaining walking elevates your heart rate in a way that going to grab a snickers in the office kitchen doesn't.
WFH is 10x better because all the commute time can be transformed in walking around the block or exercising at home instead of being in a car or public transport.
WFH is different for everyone. I used to walk to the subway, stand/pace around the platform waiting, walk from the subway to work, walk to lunch, walk to errands on the way home. Now I drive constantly around the suburbs.
People will naturally do that 5 days a week working in a city, there's no "well just go take a walk" handwaving.
WFH is 10x better because all the commute time can be transformed in walking around the block or exercising at home instead of being in a car or public transport.