Iranians are the most experienced tunnelers in the world, have been for 2,500 years.
They are well aware of the MOAB and bunker buster technology.
The minimum depth at the entrance of the nuke facility under construction near Quom is 300 feet of rock. It is fully self contained and off the grid.
They know they won’t get nuked.
What about a G-hardened sub-kiloton upgrade to the GBU-28 already delivered, based on the W33?