As was pointed out in the announcement, the trial is taking place in Germany, the Netherlands, and the UK. As for Germany, all currently approved stations that use 8.33kHz channels IRL also do so on VATSIM, I am fairly certain the same is true for the Netherlands, but the UK has held off on changing some of their stations, if I’m not mistaken. Generally speaking, however, where a frequency is on an 8.33kHz channel IRL, it will also be on that exact channel for VATSIM - other countries in the EUR region will most likely update their frequencies once the trial has been concluded successfully (which - according to the people in charge - will be rather sooner than later). For a detailed list of all currently approved stations and their accompanying frequency, you can check the region’s frequency list.