Does the cheapest steam deck have a nvme slot?

A slot that can do SATA will have the M key andor B key A slot that cannot do SATA will not have either the M or B key, but others instead

Okay, that board supports NVMe drives in all three slots If I were you, I'd diagnose further by trying the 3rd slot, or swapping into

nvme slot types NVMe: 1 Slot · SATA SSD: 1 Slot · Micro TF: Supports 32GB, 64GB, 128GB, 256GB

nvme and m2 slot difference In this video, we will take a look at SATA SSD and NVME slot and their differences