I leave it there permanently without harming the Xbox?
The upper fan is covered about 2cm.
Is that clear from the weight?
The ventilation worries me more. Although you shouldn't put anything on the console
The Xbox One S doesn't have much power anyway, it doesn't get that warm. The fan will turn up well if you turn it up. It is not recommended.
The weight of the monitor wouldn't be the problem, more likely that the fan is covered, in the long run it will overheat, the electronics won't last for a long time without being damaged. It would be better to move the xbox so that the fan is free. If necessary, two small plastic strips could be placed on the right and left under the foot of the monitor, so that there would be at least some distance to the fan of the xbox, but it is not a permanent solution.
Since it stands on the surface where the fan is not, it should work. Fortunately, I can place my monitor in the middle of my One X.