Hello, you only can use your Interrail Pass on two of your traveldays in your Homecountry (Germany) - Outbound/Inbound Rule. If you have finished this 2 days, than you need a extra Ticket from the border to your destination in Germany or from home to the border. 

thank you for the fast reply! So my plan is to do Prague - Amsterdam (going through my homecontry) and then up to the north. From my last destination Oslo I’m taking a flight back home. 

So if I understood it right, going through Germany won’t be a problem and the pass will still be valid after, as I travel through there using technically my two inbound/outbound days, right?

after useing your 2 travelday´s in the homecountry you can still use the pass in the other countries.  as said just if you travel for a 3th day in your homecountry you have to pay.

Wenn du noch nicht angefangen hast: jeh nach wohnort koennte das 9€ entw. Home-Grenze oder letzte Fahrt nutzlich sein-oder eine (super)Sparpreis bahn, je nach datum/Preis usw. darfst du alle selber aussuchen