Licorice gouramis could have problems with oxygen, of course. But then they deliberately use their labyrinth; normally they don’t use it at all. Only bubble-nest building males use it for that purpose. So if shipped, a certain amount of air must be available above the water surface, but it can be small.
They need very little amounts of dissolved oxygen in their waters. Therefore single fish or pairs can be transported in rather small plastic vessels (300 – 500 ml) without problems for one or two days; if finding a shelter (a leaf) they nearly don’t move (that’s an important point compared with many other fish!). And if the oxygen runs short they use their labyrinth. Ideal fish for being shipped. But as I said: There is the problem of temperature. That must be solved.