Officially, NVIDIA's latest motherboard design can support GDDR7 modules produced by the "Big Three": Samsung, SK Hynix and Micron (see BIOS information below). NVIDIA's market leadership likely gives it enough negotiating power to pick the best components.
GeForce RTX 50 series review samples were torn down by reviewers; TechPowerUp's W1zzard spotted Samsung's "K4VAF325ZC-SC32" GDDR7 unit (rated at 32Gbps) on various GeForce RTX 50 80 16GB models.
As outlined by VideoCardz, the rest of NVIDIA's "Blackwell" gaming product stack still uses Samsung's GDDR7 modules rated at 28Gbps, which extends to its mobile portfolio.