For Germany eBay Kleinanzeigen is your best bet, I sell exclusively through that site. As long as you’re not selling anything super special you’ll find a buyer rather quick.
I live in Berlin and I buy/sell on both, Kleinanzeigen only personal interactions though, but I did a pickup for something I bought on Reverb too. Not all Germans are fluent in English so they will use German sites exclusively.
More and more actually, I’ve seen the rise from 2014 until today. I get a dedicated Germany feed on Reverb too.
I’ve had fun learning some new German vocab and managed to register and figure out how to post an ad. But it turns out my good friend sells through a friend with a high rating / approval on Ebay kleinanzeigen, so he’ll advertise it once the item (Vermona DRM1 mk2) is in Berlin.