I installed QGIS 3.10 standalone version today and I know it has a new feature introduced in this version to export GeoPDF. But for some reason, it is greyed out.
For clarity (Windows 10)
Download the OSGeo4W (64 bit) https://qgis.org/en/site/forusers/download.html
Install as Advanced Install
Change the default GDAL to 126.96.36.199
Then in QGIS you should get the option for Exporting to Geo-PDF
Hopefully soon (when GDAL/GRASS is updated) this becomes the default in the QGIS install.
the official release qgis 3.10 is compiled against gdal 2.41, therefore this option is not available. if you need this feature at the moment there is a workaround use the OSGeo4W networkinstaller and activate the gdaldev option
please see this tweed https://twitter.com/mapperz/status/1188607950824206336?s=20