Xbox One X is powerful, really powerful, but Microsoft's True 4K claims (for Xbox One X) sounds a bit off for many reasons - PS4 Pro has been on shelves for almost 1 year and is capable of touching 4K (Native and Checkerboard).
PS4 Pro has been a big success for Sony. Jim Ryan revealed that 1 in 5 PlayStation 4 sold since November 2016 has been a PlayStation 4 Pro. This is significantly ahead of Sony's expectations. Also, 40% of PS4 Pro sales have come from those who owned a standard PS4.
Digital Foundry has provided its first impressions about PS4 Pro, detailing how it is possible that such hardware can be capable of running 4K resolution graphics. PS4 Pro is using a technique called checkerboard process, which can get a 2x2 pixel block and extrapolate a 4x4 pixel block from it.