Hello all. 
I wanted to make a request for layering option as well and, while making the video for it, stumbled upon an interesting option:
1) You can create the needed “layer” and then a toggle of the area that you intend to show. 
2) Link the content of the “layer” with the “toggle” through grouping tool.
3) You can now easily toggle the visibility of the needed layer by interacting with the “placement” of the toggle. PG UP and PG DN for speed. 

One drawback to note is that this method only works in Edit mode.
Additionally, the linked elements may have a common border outline, which can be adjusted to be larger than the key area if it is visually distracting.
Unfortunately, it is not possible to create a talk track with this example as it does not allow for editing the board during the creation process.
Nonetheless, I have found that this workaround partially meets my needs.
Happy creating!

Looking for something similar (like toggle list in notion).

I’m looking for something similar too - specifically for the Customer journey map template.  Is there a way to show/hide (expand/collapse) certain columns?

Layers is so simple to implement and so useful to make interactive diagrams (think software architecture C4) that i don’t understand why it hasn’t been implemented still now in 2023….