Even the default image would lose most pixelation if exported, please help. Just bought it on sale.

That is what happens when you use pixelate/pixelize. There is no way you pixelate an image and retain 100% of details, check the videos and gifs to see how they work, how you can use brighness/contrast or Erosion & Dilation for thing lines to give more emphasis on details, and other options to get the best results.