Hi @Jens
The wiki page you referenced lists reports and their names, and also shows how to query the options for a report in the section report actions. So for navwebpage, you can list all the options by running this command line similar to this:
.\gramps -O "Gramps sample family tree" -a report -p "name=navwebpage,show=all"
Not sure if there’s a away to extract the last used options, which are stored in the settings file gramps/report_options.xml
Hope this helps.