I actually got wifi working now
My image must have been bad somehow, as i were never able to run dietpi-config. And it wasn't offered to me when logging in via SSH. But via help from Vimtoman and a new image i got it working
After that i tried downloading the small 1.24 image again for smaller SD cards, as that would be more ideal to me. And even though i think the windows partition in that image is broken somehow (it isn't readable in windows at all), it works and boots in the Pi. I then tried logging in again via SSH, and i was then presented with a "dietpi intro/menu" that told me i could run dietpi-config. So i entered "sudo dietpi-config", and the config script launched! And then it was only a matter of turning on wifi, selecting SSID and entering the correct password. And after removing the ethernet cable and rebooting, i now have WiFi!!
So only "problem" now is the non working windows partition in the small image (if there is supposed to be one?), but this isn't actually a problem, as the Pi reads all data (including update files) from the connected USB stick.
Now i just need to find out if i can actually change the host name to something like STTNG so that i don't have to remember the IP address when connecting.
Thank you to everyone who helped out. It really was extremely simple, one i wasn't working with a corrupt / faulty image. Something must have gone wrong when i tried making the 16gb small enough to fit my 16gb cards.