Am a physio/physical therapy student so I hope to be of some help.
Sitting all day as an occupational requirement does indeed result in muscle length changes and inhibition.
In standing the hip flexors are not shortened as in sitting so long periods spent in this posture will not have the exact same deleterious effects.
Standing with good posture will not replicate the same type of imbalance and posture as produced by sitting and much to the contrary can work to reverse said posture.
Standing for long periods of time carries its own host of potential issues. Poor standing posture and poor workplace ergonomics e.g. poor work station height can contribute to the development of issues.
Having worked long hours in a noodle factory and a butcher’s I can relate to the effects of sustained repetitive postures. Even with good posture and ergonomics many hours of standing can still take a toll on the tissues of the body.
While not always practical the best way to prevent issues is by taking breaks from the postures whether with an actual rest like sitting down and eating lunch, periodic stretching and movement or changing postures but continuing to work e.g. rotating tasks/jobs.
Prevention beats management/treatment in most cases because once injured rest is usually not an option so you’ll have to work thru whatever’s going on. Often chronic issues arise and many have to live with it everyday.