APEX

Hi TFA,
In this particular case, it does not matter whether user is using mobile or laptop or monitor. The issue you are facing is because of window width. You can get window width using jQuery $(window).width()
You can use blow code to unfreeze a column using JavaScript

// IG Static ID emp
// ENAME is column name that has to be freezed, unfreezed conditionally
var grid$ = apex.region("emp").call("getCurrentView").view$;
grid$.grid("unfreezeColumn", "ENAME");

You can use these two techniques to achieve what you are looking far..
Create dynamic action which fires on page load event, create true action which executes JavaScript code. Put below JS code in true action

// IG Static ID emp
// ENAME is column name that has to be freezed, unfreezed conditionally
var grid$ = apex.region("emp").call("getCurrentView").view$;
// here I am unfreezing column when window width is < 600 pixels
// change it based on your requirements
if ($(window).width() < 600) {     
  grid$.grid("unfreezeColumn", "ENAME");
}
else {
  grid$.grid("freezeColumn", "ENAME");
}

In addition, you can also execute this when on window resize event or using APEX event apexwindowresized 
Regards,
Srihari