Drills can obviously be sharpened but what makes then useless is worn out lands causing them to jamb.
There is a way of still using them for start holes for boring where size is not an issue, it is quite simply to sharpen them by hand deliberately slightly off centre, by hand this is easy.
They will cut an oversize hole and will not bind in use, you will see only one swarf coil emerging, this only works for the larger size MT drills where an element of stiffness exists, which are also the most expensive to replace.
I can not claim credit for this tip as our toolmakers did this and some of the drills were many years old, seems wrong and crude but it works and helps with a tight budget.
I can see any comments on this may be interesting.