So, can I just start reading this book chapter-by-chapter implementing what I learnt in a language of my choice? What is the optimal way to go through this book?
Totally, you can do it. But the book is so huge that you will miss most of the details. However, you can use it as reference. First follow the ray tracing in one weekend to get the overall idea of path tracing. Then you can start with PBRT.
As for language of choice, anything will be fine. The book will build up a solid foundation. The only thing that can stop you is the amount of frustration which you may face when not figuring out the things. It can be confusing at times, but please give your time and let it sink in. After sometimes, you can review it with a completely fresh eyes and you may fix a lot of issues!
The one thing to keep in mind is that even though it's written in a literate programming style, it's not in order. So implementation in your own language (say, Rust) is completely possible, but it won't be easy. Especially since the book's code is optimized and idiomatic C++, and that can make it challenging to get past the borrow checker.
The code in book is in C++ and several of the exercises assume you are experimenting with the provided renderer. I seem to remember at least one exercise caused me to learn quite a bit about AVX intrinsics to see if I could beat the compiler at vector math.
Rust may be tricky because you will need to render pixels in parallel, and most higher level languages will take a lot of skill to make fast.
As for language of choice, anything will be fine. The book will build up a solid foundation. The only thing that can stop you is the amount of frustration which you may face when not figuring out the things. It can be confusing at times, but please give your time and let it sink in. After sometimes, you can review it with a completely fresh eyes and you may fix a lot of issues!
Goodluck!