Is there an open drain buffer/device that has schmit trigger CMOS input?

The nearest you can get is SN74LVC1G99 with A=B=C=D=low, OE = input. However, this is not a true open-drain output because the voltage in the high-impedance state is not allowed to go above V_CC.

Hi Emile,

Clemens suggested implementation will work for this. It is true that the recommended max is VCC however the abs max for output voltage in the high impedance state is 6.5 V. The issue that could arise if you do plan have the output go above VCC is if somehow the output drives high then current can conduct through the parasitic diode of the pfet. If the inputs are tied low and the pull-up value is large (~10kohm), this shouldn't cause much concern.