The first six textbook chapters (all the hardware stuff) are available on the website in the 'Projects' tab, you should buy the book for the other six. All 12 chapter assignments are available on the website. The Software section has a hardware simulator to test your designs.
I'd like to second this -- I'm slowly making my way through Nand2Tetris (currently building a VM -> assembly transpiler, and if you'd asked me to do that a few months ago, I'd have had no idea what you were talking about), and it's been really fun, taught me a lot about low-level computing, and given me the opportunity to learn a new language (I'm building everything in C). I highly recommend it!
The Elements of Computing Systems / From NAND to Tetris https://www.nand2tetris.org/
The first six textbook chapters (all the hardware stuff) are available on the website in the 'Projects' tab, you should buy the book for the other six. All 12 chapter assignments are available on the website. The Software section has a hardware simulator to test your designs.