owc ministack stx

The OWC miniStack STX contains one 4TB NVMe SSD and one 256GB SATA SSD. If I connect the thunderbolt cable from the STX to a USB3-A type output on the Mac Mini via an adapter, only the 256GB SATA disk is visible to PVE. And so is also the case if I boot up the Mini using Linux Mint 22.1 install...