m_kos parent
I am teaching intro stats and would love to have a textbook that introduces equations in this manner. I have been trying to incorporate this style into my slides but it is not as easy as it looks. (Same issue with syntax highlighting in PowerPoint/Google Slides.)
I have had some success with PowerPoint animations. Put up the equation, and for each mouse click surround the symbol(s) you want to explain in a red box or something and have a infobox show up (which can also contain images, such as plots - very helpful). As you transition to the next symbol(s), fade away the previous infobox and surrounding box.
You might be interested in the work of Andrew Head, in particular his team's Formula Formatting Language: https://andrewhead.info/assets/pdf/ffl.pdf - I have not tried it myself though.