My ThinkPad-P16-Gen-2's ubuntu22.04 kernel is 5.15.0,which cannot successfully install nvidia driver with commad:

sudo apt install nvidia-driver-545

To solve this problem, we have to upgrade the kernel from 5.15.0 to 5.19.0 which you can download from:Index of /mainline

and then use the following command to install the 5.19.0 kernel in the folder:

sudo dpkg -i linux-*

sudo update-grub

and then reboot the laptop to ensure your ubuntu22.04 is using kernel with version 5.19.0.

when it comes to install the nvidia driver, you should follow the traditional way like below:

sudo gedit /etc/modprobe.d/blacklist.conf

blacklist nouveau
options nouveau modeset=0

sudo apt-get update
sudo apt-get install build-essential

After the update，input the following command to check whether nouveau is turned off.

lsmod | grep nouveau

If there is no output, it means sucess, or you should reboot your laptop.

then use the following command to install nvidia driver

sudo apt install nvidia-driver-545