Taste and olfactory are matters of chemical compositions. It will take an incredible effort but something similar to a mass spectrometer can be used to detect every taste and smell we can think of and beyond. How fast and how efficient they can be is probably the main challenge.
Touch is difficult. We don't even know fully why or how does an itch "work". But force, temperature, atmospheric, humidity sensors, etc are widely available. They can provide a crude approximation, imo.
Just off the top of my head. I am sure smarter people can come up with much more suitable ways to "embody" a machine learning model.