Thanks for watching! If you want to support me, you can wishlist the game I am working on:
https://store.steampowered.com/app/2473640?utm_source=yt_mezaka&utm_medium=web

@lucas_roedel made an improved version of the addon:
https://lucasroedel.gumroad.com/l/pixel_art

Addon Download for Blender 3.0:
https://drive.google.com/file/d/1Wwrrl7one7BwAsicYYbEFdyHvijqwy5Z/view?usp=drivesdk

Watch the first video:

If your image is blury when you open it in other programs it is because it has a low resolution. I generally use https://www.getpaint.net/ and then upscale it using Image-Resize-Nearest Neighbor-1000%
But any other Program that can upscale using Nearest Neighbor will work!