When you point out that Hijab covers the face but Janeu doesn't, you are deflecting. Hijab is not being banned in schools because it covers the face. It's being banned because it is religious. That's why the court judgment was about "essential religious practice".
Those who try to make it about faces being covered are being dishonest by ignoring the religious aspect of this matter. The Janeu and Mangal Sutra being compared to the Hijab is absolutely valid because they are religious practices and are allowed in colleges. Men wear Janeu to colleges and married women wear mangal sutras to colleges too.
In addition, government schools and colleges have Hindu religious prayers, and government offices display Hindu deities pictures and statues. Using these things as examples when questioning the validity of the Hijab ban is valid.
Now, I am not worried about the garden variety troll who is going to type "cope" because that is a word he learnt from an IT cell google doc yesterday. But if you are someone genuinely worried about religion being kept out of public spaces, you should not fall for this deception.