Now I'll answer the question myself and for others if they are interested.
The current offer is delivered with a Swiss plug.

As we didn't want to wait for the answer and still wanted to take advantage of the 20% voucher, we called Galaxus customer support. They said it was a Schuko with adapter.
Would actually be perfect as it was intended as a gift in Germany. Ordered yesterday, arrived today. Plug? Switzerland.

Device goes back as not as expected. A corresponding review regarding product description (unfortunately often wrong at Galaxus) and ignorant support follows via the account of my partner (buyer).