It’s taken me a long time, but I finally found a “local” NaNoWriMo group!
In the US, where NaNoWriMo originated from, so-called “Write-Ins” take place in many cities throughout the country, with several options per state.
Unfortunately there are fewer NaNo participants in Germany, and finding a group near you can be difficult.
I searched the forums this year, because I couldn’t find a group that I could feasibly get to last year. And then I discovered a girl asking whether anyone from Leverkusen and surroundings wanted to go for a coffee.