NO_PUBKEY F37D203008A7D361 when installing CUDA

Accelerated Computing CUDA CUDA Setup and Installation
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I’m trying to install 12.9 into Ubuntu 24 for x86 based on this URL

On step:
sudo apt-get update

I get the errmsg which I have no idea how to fix.

W: GPG error: file:/var/cudnn-local-repo-ubuntu2204-8.9.7.29  InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY F37D203008A7D361
E: The repository 'file:/var/cudnn-local-repo-ubuntu2204-8.9.7.29  InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: https://download.docker.com/linux/ubuntu/dists/noble/InRelease: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details.
W: http://ppa.launchpad.net/deadsnakes/ppa/ubuntu/dists/noble/InRelease: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details.

Google AI suggested:

sudo curl -sL https://developer.download.nvidia.com/compute/cuda/repos/ubuntu2204/x86_64/3bf863cc.pub | sudo gpg --dearmor -o /usr/share/keyrings/nvidia-cuda-keyring.gpg

but I still get the same error.

I’m clueless about this sort of thing, so I don’t know how to about fixing this

[added]

Google further suggested:

sudo cp /var/cudnn-local-repo-ubuntu2204-8.9.7.29/cudnn-local-08A7D361-keyring.gpg /usr/share/keyrings/

which seemed to help but now I get the warnings

W: https://download.docker.com/linux/ubuntu/dists/noble/InRelease: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details.
W: http://ppa.launchpad.net/deadsnakes/ppa/ubuntu/dists/noble/InRelease: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details.