I strained both my feet during one of the lockdowns (a period of inactivity followed by too intense activity). I have been unable to walk well since then. I used to work full time in the office making about 12k steps a day (+ about 10 km of biking). I never had any issues but now that I can't walk well I often make about 2-3k steps a day and I am starting to have pain in many places in my body. When I take painkillers and go to the office, I make about 5500 steps and I feel better after just a day already.

My point is. Buy a tracker, make some notes about how you feel (or just, develop a feeling for the numbers by checking them regularly). I guess for me the truth is: Prolonged periods of over 10k steps are fine. Long periods of around 2000-3000 steps are detrimental to my back and other parts of my body. But your body may be different and you may for example move more while sitting.

I'm trying to be creative in moving around now while working from home. It is much harder and requires more discipline then being in the office but the alternative is slow decay of my body. In any case, I find 10k to be a nice goal, call it unscientific but I bet that a proper scientific method would come to a similar estimate.

Btw, I'm actually pretty sure that my Amazit Bip U Pro does not even count my steps exactly, but it's a good proxy for "activity", imho, as 10k steps is a good proxy for: be (more) active.