In my opinion that is poor value. It has a low end tourney derailleur and what looks like a freewheel typical of a sub £100 bike.
In UK money that is something like £450 but you can get a much better bike with 8 speed freehub drivetrain with Claris derailleur for half the money and seems to match or exceed the Dahon in every area except no rack or mudguards.
ALLOY FOLDING BIKE - Greenwaycycles
I wouldn't expect to pay £450 approx and get a tourney derailleur and such low end parts.
I don't know what else is available on the German market. I would at least look to get a Dahon with an 8 speed drivetrain. The Dahon looks like a very entry level bike with too many low end components.
Had a quick look on amazon germany and found this for 400 euros.
https://www.amazon.de/KLAPPRAD-FALTR...s=folding+bike
Nexus hub so no derailleur to damage on a pavement edge etc plus much easier shifting at any time. Normally you have to pay a premium to go from derailleur to hub gears but it's actually costing you less money.