I'm very impressed with the new GeoPDF export capabilities of QGIS 3.10 (Windows 10). Now we can create Vector-GeoPDFs with layers included!
With the help of GDALs "Geospatial PDF" file format documentation (https://gdal.org/drivers/raster/pdf.html) I managed to reimport a GeoPDF, which I exported from the Layout Manager, turning on and off certain layers. Therefor I use DOS Environment variables to turn on (GDAL_PDF_LAYERS) and turn off layers (GDAL_PDF_LAYERS_OFF).
The GDAL command gdalinfo -mdd "all" helps to find all available layer names.
Unfortunately, I cannot hide all elements outside my layers (i.e. scale bars, legends, titles, etc.).
So my question:
Is there any hidden layername, or is there any GDAL trick to filter these items?
P.S.: I don't want to crop the image using the PDF NEATLINE entry, which seems to be incorrect anyway (the vertex coordinates of the polygon are in wrong order)