Yes, you can add some transparent liquid floor cleaner to the water in the water tank. We do not recommend any specific liquid floor cleaner. 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 avoid damaging the appliance, never put wax, oil, descaler or floor maintenance products that cannot be diluted in the water tank, or let the appliance pick them up.