I made a real time Sudoku solver using the camera, it looks for the edges of the Sudoku in the frame, extracts it, solves it and overlays the solution on the puzzle itself. For the digit recognition, I used a CNN, trained using Keras with printed characters from the different ubuntu fonts. For the image processing part, I used OpenCV for the edge detection.
this youtube channel helped me a lot : https://www.youtube.com/channel/UCn09iU3hS5Fpxv0XniGv2FQ