Theoretically: isn't it possible to categorize these devices in Germany as normal gas-schreckschusswaffen mit PTB in circle?
The PTB is "guarding" on the possibility of converting gas-alarm guns to real ones. In case of these fulid jet guns, it is impossible because they made of plastic and their entire construction.
Of course, the caliber is not CIP gas-alarm caliber, however, there are other PTB which also NOT, such as the HK Notsignalgerat:
(In this case you'll need KWS for carry, but the devices became free to own.)