How to Import Stuff from Pyxel Edit
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(1) Save the Pyxel Edit project somewhere just to not loose it.   For example to slime.pyxel 
(2) File -> Export -> Export tileset..   For example to slime-tileset.png
(3) File -> Export -> Export tilemap..   For example to slime.json
(4) Copy slime-tileset.png file to unity Assets/Resources/spritesheets/ folder. (Sorry, does not work outside Resources)
(5) Copy slime.json file to unity Assets/Resources/levels/ folder. (Sorry, does not work outside Resources)
(6) In Unit, click on tileset sprite and then
   - Change property "Sprite Mode" from "Single" to "Multiple"
   - Click on "Sprite Editor" button -> Slice -> Set Type="Grid by Cell size" and PixelSizeX=48 and PixelSizeY=48. 
   - Then click "Slice" button and then "Apply" button and then "x" button to close Sprite Editor.
(7) Set FilterMode=Point and Format=RGBA32 bit
(8) Done! :-)    
   - The script SpriteManager.cs will take care of loading / managing the sprites in the sheet.
   - The script LevelLoader.cs will take care of loading grid data from the json file.
