Danik
I don't know about any free importers, and I haven't tried it myself yet, but it should be fairly straight forward to do I think.
For importing the tileset using Unitys sprite editor maybe this tutorial helps
http://jessefreeman.com/game-dev/introduction-unitys-new-2d-workflow/
Here is an example for importing a json tilemap in AS3 that you might be able to port. Perhaps C# has better support for XML than JSON, not sure.
https://github.com/Danik/Pyxel-Edit/blob/master/examples/as3/TilemapLoading.as3
I might try this and put up a simple example soon.
For importing the tileset using Unitys sprite editor maybe this tutorial helps
http://jessefreeman.com/game-dev/introduction-unitys-new-2d-workflow/
Here is an example for importing a json tilemap in AS3 that you might be able to port. Perhaps C# has better support for XML than JSON, not sure.
https://github.com/Danik/Pyxel-Edit/blob/master/examples/as3/TilemapLoading.as3
I might try this and put up a simple example soon.