That's not exactly true, they can be "unlocked" but not many people have tested and verified that the unlocked memory is stable and/or useful.

But the cards themselves are extremely limited in function, necessitating either board level work to reconnect the electrically disconnected traces or transplanting the hardware to a new board. It's anything but plug and play.

https://niconiconi.neocities.org/tech-notes/nvidia-cmp-170hx...