Nut clips are also fun. (threaded-shank clip nuts)
They typically don't strip, rather the back half will fracture away from the front half, and the bolt just spins. Always best not to put excessive force on the bolt.

Things to try: soak with penetrating oil well prior to removal attempt

Apply heat to nut, cool with penetrating oil.

Grip back side of nut with needle nosed vise grips

Rock it back and forth

If none of these work, or you already broke the clip, drill a hole in the nut equal to the shaft size. The head will fall off the bolt, and the bolt shaft and clip will fall out the back.