It finally happened! 1 week too late but I managed to get a GSC above ground.
So after the first seed just did not come out of the soil despite that it germinated in water, I popped another seed. Since I was out of home for 4 days, the taproot reached a length of 5 cm so I could not plant it inside an EazyPot. Straight into the soil it went: in its 3gal (11L) end pot. By doing that, I damaged the taproot on its tip because it was long and stiff. This obviously never happened before since this is my 2nd grow but I was confident that the seed still will make it because of the sheer length and thickness of the taproot. And I was right, the seed came out of the soil only 1 day after planting it in. It needed to open up itself over night and today, I consider it born (Day 1).
I really hope that it just continues with not giving any fucks and is growing into a beautiful plant.