And keep the layers while grouped. that would be very useful.

This would keep sorting, ordering, overlapping etc intact

Would be a really great feature to keep layer structure, when grouping elements.
At the moment everything grouped automatically collapses into one layer.
The simplest way to explain it would be similar to having saved selection sets.

The benefits for grouping across layers include:
Managing different components/groups of design elements while retaining layer hierarchy
Keeping grouped colours or thicknesses or object types separate
Being able to transform a selection without losing layer order, and without losing that selection later.
Having visual layering and overlapping keep fidelity
Keep elements apart for animation(after effects) but grouped for control in illustrator

Please consider adding this as it would be very useful.
In my current workflow I group elements that have been sorted by layer, group to keep these together, make changes(size, position and artwork changes), then once all groups have been finalised, ungroup and sort into layers again. usually over complex artwork/designs/scenes.

A workaround solution we have today is a script by Sergey Osokin, which stores the original layer of each object when run before distorting and reordering the objects back when run after — https://github.com/creold/illustrator-scripts/blob/master/jsx/RememberSelectionLayers.jsx
It won’t work for sublayers though.

I am just gonna note that any attempt to fix this should probably be tested against multiple paths grouped from across multiple, nested layers, like this:

Layer 1
- selected path
Layer 2
- Layer 2a
--- unselected path
--- selected path
--- unselected path
Layer 3
- Layer 3a
--- a bunch of unselected paths
- Layer 3b
--- some selected paths

This would be so handy!

This would be so helpful and save so much time! :]

It would be great if you could group multiple objects on multiple layers and have them redistribute to the original layers when ungrouped. For Example, you have multiple elements that you want to center on the page as a group, but then want them back in their respective layers.

Yes please to "Ungroup remembers Layers" in Illustrator and I would also suggest that Indesign inherit the "Save selection" feature from Illustrator, while we're at it.

literally can't believe this still isn't a thing

long, long time ago, Freehand had a great function (indeed it hat a lot of great functions that I am still missing in Illustrator): When you grouped Objects from different Layers, it remembered the original layers of these objects. So you could group them, do with them whatever you wanted and after ungrouping all objects went back to their original layers what was a very useful function. I whish, Illustrator wound offer something like this, too...