This would be amazing. As others said, it's a great way to visually browse through big decks if you can collapse chapters together. Even if not possible to collapse, purely being able to see the indentation would make a world of difference.

Yes, I also have sections and I used this in Keynote all the time!

+10000 this would be super useful. We have a deck that has a LOT of slides, and it would be great to group them into sections (rather than entirely separate decks)

biggest missing feature that is preventing me from switching from Keynote.

I add to this. It would be immensely helpful to group slides together. It would also be useful to color code the groups to make them visually identifiable. It gets cumbersome when there are too many slides, like a speaking presentation I have that contains over 100 slides.

Oh yes! And being able to "name" those sections for better readability, without creating an additional slide for that.

Yes please. One of my favourite functions in Keynote.

This could work nicely for me. I end up building huge decks for my projects that span many areas. Even if it were just a visually organising of the slides would massively help.