Smallest Footprint Source Only (No Sink) Buffer Solution
Invert the problem by turning your pulldown resistors into pullup resistors, then you can use a sink-only buffer: the good old UNL2*03 or even better a shift register with open drain outputs, or I2C IO expanders if you like I2C. Note some of these support making the pins in/out/HiZ so that would also answer your original question, to source current set the pin to output &quot;1&quot; and to not source (or sink) anything, set to input.
Another option would be to use a micro as many IOs as you have pins in your cable, then you can control the sink/source/hiZ status of each pin independently.