I just throw an old skateboard deck on my firm foam roller… it doesn’t offer fore/aft movement but it’s good for balance and core engagement.
A standing desk is good for variety, but like anything, can be too much of a good thing. I generally do only about 20 minutes at a time. It helps relieve certain hip/leg/knee issues i get from sitting too long. But on the other hand, can cause other hip and lower back issues if I stand too long and don’t focus on my posture or get fatigued. I haven’t tried a balance board, but adding good sneakers has been key. Also, I have a cross-bar and a foot rest for sitting that allows me to vary my position - like this.
An unexpected benefit as well is in between heights for the desk. Sometimes I adjust my chair to be higher or lower and adjust the desk accordingly. Gives more variety for the seating position.
Not saying this would be good training for serious athletes but for time crutched people with normal jobs like me a treadmill might be good enough to reach into zone 2 to get some of the benefits while working.
Thinking a normal level treadmill would require a running gait to get hard enough to be in zone 2 but an inclined treadmill could allow you to reach zone 2 while still in a walking gait so should be able to use a computer on a standing desk (head movement and arm movement differences between the two gaits)
Or am I being too optimistic (ok, lazy) thinking I can get some useful exercise while working and walking through meetings while working from home. I’m guessing higher level athletes may be too in shape for that to count as a workout but if my ftp on the bike is ~2.5 watts/kg…