The Jupyter Extension provides an extensibility point allowing other extension to access the Jupyter Kernels.

When an extension attempts to access a Jupyter Kernel, the user will be prompted to grant or remove access to the Kernels.
Access to Jupyter Kernels is granted by the user per extension. Meaning the user can grant access to extension A and revoke access to extension B.

Granting access to Jupyter Kernels, give that extension the ability to execute code on that kernel (local &/or remote).

Users can manage (gran/revoke) access to the Jupyter Kernels per extension via the command Jupyter: Manage Access To Jupyter Kernels.