So is studying all that stuff just for being a MLE/ data engineer worth it, if you are already a software developer (full stack)?
I think this varies pretty widely based on employer, e.g. if you are at a smaller company (and you show interest and have the necessary skills) then you're much more likely to be able to contribute on the modeling side. It's easier to get there if you have an advanced degree, but definitely not necessary.
That being said, IMHO book lists like this aren't very useful because there's no incentive to keep them short and realistic. Reading seminal papers and implementing them is a different learning philosophy, maybe, but lists like this are probably more feasible to complete: https://dennybritz.com/blog/deep-learning-most-important-ide...
however, it remains intrinsically very interesting and can be fun to learn about. more so than most resume items.