In Luxembourg, the government says, the HPC sources are still scattered around the country. That is why they envisage a national supercomputer in a national supercomputer centre.
The EuroHPC allows the participating countries to decide freely on the level of their contribution, when they join, and when they will leave the JU.
In the Luxembourg press it was speculated whether one of the pre-exascale or exascale machines will be located in Luxembourg. Although not impossible, it seems very unlikely, as there are major HPC supercomputer centres in Europe that have the infrastructure and support in place to just "drop in" such a machine.