Usually at the most, I will bring a "universal" kyusu, glazed, some small cups, some teas in small sample tins (or just one).
Or ... I will use some fill your own bags.
Or ... I will take some tea and use the coffee cup/saucer as a make shift gaiwan, pouring into a second cup.
There are more options that I have considered, but these 3 are what I do.