Is it permissible to wear the niqab during Umrah while feeling extreme discomfort and a lack of khushu' (devotion), and is it permissible to cover the face with a scarf due to the inability to uncover it in the presence of men?

It is not permissible for a woman in a state of ihram to wear a niqab, litham, or burqa. It has been narrated from Aisha that she said: "Do not wear a litham or a burqa." It was also narrated from her that she said: "A woman in ihram may wear any clothes she wishes, except a garment touched by rose or saffron. She should not wear a burqa or a litham, and she may let her garment hang over her face if she wishes."

Al-Shafi'i mentioned in Al-Umm: "She should not cover her forehead or any part of her face."

The psychological feeling of distress does not justify wearing the niqab or uncovering the face in front of non-mahram men. A woman in ihram can let something light hang over her face, enabling her to see while keeping it slightly away from her face.