In Draw, export to PDF should have an option to keep (or not) internal LibreOffice layers to PDF layers, called OCG (Optiona Content Group) in PDF 1.5 specification
Steps to Reproduce:
1. open Draw
2. create 2 layers
3. create an object in layer 1
4. create an object in layer 2
5. export to PDF
open PDF with Acrobat DC, the PDF has no layer, and all object was collapsed to a single PDF layer
the PDF should have 2 layers, so using a Reader the user can enable or disable single layer
User Profile Reset: No
Scribus 1.5 support exporting to PDF, setting PDF v1.5 and activate Layers option
Created attachment 167210 [details]
a PDF that is multi-layer, with visibility selection panel
You can get such pdf, when you open the .odg file in Scribus and let Scribus export it to .pdf. So it is possible.
But you need to keep in mind, that "layer" in Scribus or PDF is not the same as "layer" in Draw. "layer" in Scribus define a stacking order. That is not the case in Draw. In Draw, "layer" is a kind of bundling objects in regard to visibility, printing and locked state and that is independent from grouping and from stacking order.
Nevertheless I think it would be a nice feature for Draw.
Created attachment 167215 [details]
two layers drawing
if LibreOffice PDF export will preserve internal layers, objects stacking will be controlled in LibreOffice, and will be preserved in PDF, like now.
The plus/my need is to have layers that can still be disabled in PDF viewers
Created attachment 167320 [details]
a simple draw exported to PDF with Scribus keeping the layers