Install KDE Neon on top of vanilla Ubuntu 20.04

install-kde-neon-on-ubuntu-2004.bash

#!/bin/bash

# SPDX-License-Identifier: BSD-2-Clause
# SPDX-FileCopyrightText: 2020 Theo Markettos <git@markettos.org.uk>

# Script to install KDE Neon on top of Ubuntu 20.04
#
# The KDE Neon site says "A web search should quickly give you relevant information on how to do this. "
# but I didn't find any, so worked it out from first principles

# add the KDE Neon repository
wget -qO - 'https://archive.neon.kde.org/public.key' | sudo apt-key add -

cat <<EOF > /etc/apt/sources.list.d/neon.list
deb http://archive.neon.kde.org/user/ focal main
deb-src http://archive.neon.kde.org/user/ focal main
EOF

# pin base-files to not install the Neon version
# - this prevents the install identifying as Neon,
# and stops problems with programs that this confuses,
# eg the Docker install script 
cat <<EOF > /etc/apt/preferences.d/99block-neon 
Package: base-files
Pin: origin archive.neon.kde.org
Pin-Priority: 1  
EOF

apt -y update
apt -y install neon-desktop

The file https://archive.neon.kde.org/public.key doesn't exist anymore.

The file https://archive.neon.kde.org/public.key doesn't exist anymore.

this file does indeed exist because I literally just downloaded and added it.

It exists now. It was showing me the 404 error for some reason at the time.