What’s the output of nvidia-smi? If it’s a newer laptop you might need to add a machine owner key so that secureboot will allow the required dynamic kernel modules to load. In debian the module will be signed with the dkms signing key, adding it as a MOK is fairly simple. wiki.debian.org/SecureBoot#Making_DKMS_modules_si…
*Try disabling secureboot first, if things start working re-enable it and follow the advice above.