Your rig doesn’t have 15w40 and 4 gallons sump of oil….it’s 0w20 cold in a pan, even with the block heater. The block heater will never warm the oil. The startup wear is exactly the same.
Here's a figure from a study on cold oil flow during engine cranking. This is with a 10W-40 oil at -25 C, and the results should be similar to using a 0W oil at -35 C. It shows that using a block heater for only 1 hour greatly reduces the time required for oil pressure to build up in the top end of the engine during cranking. Typically block heaters are used for around 4 hours, which would have roughly double the heating effect compared to this test.
On a modern engine with an oil-coolant heat exchanger, block heaters will increase oil temperature by a lot more, and the benefits of using a block heater should be even greater. 4-5 hours of block heating time increases oil temperature by 18-20 C on my car.