The 4 output sockets have a "household-compliant" voltage of 220 volts (but I have not measured this directly, but all applications work the same as with mains power).

If you "illegally" use a Schuko to T13/T23 socket adapter, it is like this: If the unit is connected to the house mains ("UPS") and switched on: TN mains with phase (L), neutral (0) and protective earth (PE) - as usual. So 230 volts between L and 0 and between L and PE. But 0 volts between 0 and PE. However, when the unit is not connected ("camping"), an "IT network" is present with L1 and L2 (no phase or 0 conductor). 230 volts between L1 and L2, but between "PE" and L1 or L2 are 115 volts (approximately). "PE" in inverted commas because there is no protective earth in this operating mode. Therefore, officially only 1x Schuko to 2-pole would be allowed. If you want/need to do it differently (e.g. T23), you should consult a specialist. T13 is not really possible because the unit supplies more than 10A.

Thank you very much for your answer.