Just to point, but it would require actively cooled helium. You can't just drop it in liquid helium and expect boiling to cool your device.
Can you make a closed loop helium cooler? Also, that level of coldness seems like it would have negative interactions with other components.
> Can you make a closed loop helium cooler?
An MRI machine is a giant magnet with a closed loop helium cooler to keep the superconducting coils cold. A chiller is used to reject the heat outside.