Remember the steering wheel itself is soft steel. Alot of your efforts is wasted on flex. No im not jking.
Spray that shit with wd40 let it sit for 20mins. Get a socket slighty larger then the spline and hit the steering wheel on further, yes further, then grap that fuker at 9 oclock and 3 oclock and wiggle side to side pulling towards you. And yes leave the nut partially on as too not bust your head.
It will come off. Works for me everytime. When you reinstall the steering wheel put some grease on that shit so its easier next time.