the clear will chip/scratch same as the paint will ...and the thicker the coating the deeper and worse the chips will be
only time ive done it is when paint is running low and not enough left to give a wet coat , so add a bit of clear to the paint and carry on for a wet coat
I'd avoid lacquer where possible. It's less likely to lift on top of gloss 2K than over base coats, but lifting is common after a number of years, especially after a few stone chips, looks ugly. Also lacquer is much more difficult to repair than a straight gloss colour.