I've given Griffin every drink that appeared in the list for me, and nothing seems to have changed so far after the first one. I tried talking to him in between each one, to no changes. Possibly there will be something different tomorrow, when I can try to buy cyberware again. Maybe he likes me more and will have more options available?
Edit: On the first day I had two options, eyes and arms. Today I've got four options, for cat eyes, spidery limbs, tiger paw and transparent legs. So maybe giving more drinks gets you more options to choose from?
Edit: Today's choices were fixed eyes, tiger paw, transparent arms, transparent legs. So looks like it may be random, rather than one of each type (excluding neural and organware). Bought fixed eyes.
Next day: fixed eyes, tiger skin, tiger paw, transparent arms. Bought tiger skin.
Next day: black wings, spidery limbs, tiger paw, transparent arms. I bought the black wings, but got a cat eyes result. Guessing they're supposed to be the dark wings.
Skipped a day, then next day: dark wings, spidery limbs, transparent arms, transparent legs. Bought spidery limbs.
Next day: cat eyes, spidery limbs, transparent arms, transparent legs. Bought transparent legs.
Next day: dark wings, fixed eyes, tiger paw, transparent arms. Bought the arms.
Next day: dark wings, cat eyes, spidery limbs, transparent legs. Bought the legs.
Next day: cat eyes, tiger skin, tiger paw, transparent arms. Bought the transparent arms.
Doesn't seem to be too much in the way of a pattern that I can see, but I'll keep recording data points for the time being.