The picture above is the SN74LS06 schematic from Texas Instruments. It appears that the input of the SN74LS06 can be connected to an open-drain output.
I purchased the 74LVC06APW from Nexperia. But I don't get any message about design unity.
Are all 74LVC06 and 74LS06 devices compatible? Can I connect the input of the 74LVC06APW to an open-drain output? Or it is better to add a pull-up resistor?