Hello,
I use Kontact with the akonadi_google_calender resource and it works very well.
I would like to have a copy of the google calender in a local .ics file. I know that I can access the .ics file via google, but google dosen't provide categories where Kontact does.
Thus the question if akonadi can create an .ics from the google calender with its additional data (like the category)?

I believe FIle > Export as iCalendar would do what you want. But of course, it would be "static" at the moment you export. Were you thinking of something more dynamical?