I completed the hardware part last month. It's definitely accessible and serves as a good entry project for interested students. However it glossed over a lot of things (that even I'm aware of) so I decided to up the game and find other projects/lectures. The CPU project of University of Tokyo seems interesting but is too tough for whoever just completes nand2tetris. Some bridge project is needed.
Thanks! That's part of the picture. I'm looking for something similar to nand2tetris but level up one notch. 539kernel definitely can serve as part of the puzzle.