Yes, you can add some transparent liquid floor cleaner to the water in the clean water tank. We do not recommend any liquid floor cleaner in specific. If you want to add a floor cleaner, use one that can be diluted in water. Use a low-foaming or non-foaming floor cleaner that is suitable for your hard floor.
Note: To prevent damaging the appliance, never put wax, oil acetic acid (vinegar), descaler or floor maintenance products that cannot be diluted in the clean water tank, or let the appliance pick them up.