I don't think they have. I have argued for nitriding in the past. Though when push came to shove I decided against nitriding my Tikka actions in stainless.
I would be more inclined to nitrided CroMoly. Nitriding barrels makes a lot of since to me. That leaves the action to protect your face. I thought about nitriding the bolt, but having bolt lugs shear sounds bad.
I would have no issues nitriding a 223 (more metal, less pressure on the lugs due to smaller bolt face area). 308 and Creedmoor based cartridges don't particularly worry me, but I think I will pass. Magnum bolt face cartridges do worry me.
If I had the money, I would get 12 tikkas, 6 stainless in all three bolt faces, 6 CroMoly in all 3 bolt faces. Then nitrided half of them and carry out destructive testing just for fun. I don't have the money, so instead you just get my guess.
I would be interested in seeing how they handle a double charge of a fast powder that is cartridge appropriate and in how they handle a bullet stuck in the barrel with a warm load someone might actually use behind it.
If they survived those, in that order, then I would move on to dumb stuff until they failed catastrophically (such as a case full of handgun powder and a plugged barrel).