Elderly with decreased memory/ vision

I would really like to see an easier sudoku puzzle book ( 4x4, 6x6) in large print, to offer to my father and my father-in-law, who both have limited ability to attend to a task for a long enough period to complete even an easy 9 block sudoku. It would be great to see them have success at a puzzle, but not have it be called a "children's" puzzle. They need large print due to poor vision.
I think this type of puzzle would be a huge blessing in many assisted living settings where we see a lot of declining cognition, but folks are still able to complete smaller tasks and need to have successful completion to keep them going.