Does the SEEK, fast forward, or ANY of the control buttons supposed to work when playing bluetooth audio?

My crappy $50 Blaupunkt on my beater Benz can do this (fast forward, pause, etc.), but I can't figure out how to do this in the G.

 

Yes, depending on the device and audio application... I can skip songs, change volume, and press the enter button from the wheel. Podcasts skip 15s at a time, or sometimes it skips to the next episode. 🤷 On the console, play, pause and skip work, but seek doesn't do anything.
Of course, things have changed as Bluetooth drivers are updated and OSs have changed... Ymmv.

 

Does it work for you with Pandora?

 

The website, no, i get no functionality from anything but the phone.... on the app, sometimes 'skip' works. Though, I don't use the paid version, when an ad plays, volume is the only thing that functions.
Im on Android Pie, using a rooted OnePlus 5. I mainly use Spotify, where volume, skip, and play/pause are the only functions that work.

I think most, if not all Bluetooth issues with this -- and other cars -- are app, bluetooth-driver, OS, and device specific. It will likely be very difficult to pin down exactly how to solve your issues unless you have a few devices and some app-development skills laying around.
All the more reason to swap an Android Auto tablet or RaspPi into the car, if you really want every bit of function.