For once I’m inclined to believe them on this. Purely because Sony has had a good track record on allowed off the shelf HDDs in their consoles as opposed to the 360s BS.They repeated multiple times "do not go and buy any drive, we are working with drive makers to certify them with the ps5" in theory they need to be pcie4 7gb+, the extra speed is required to relinquish the control to the internal specialized controller without any problems.
On the other hand, Sony have also been huge idiots about their proprietary memory cards on the PSP and Vita.