Wireguard is a new VPN solution included right in the Linux kernel. It’s part of the mainline kernel since version 5.6. Debian Bullseye has Linux 5.5, but the distribution maintainers decided to backport Wireguard, so it’s already available by default. Sadly, this broke the installation process that is usually suggested on the Internet.
Sometimes it’s handy to copy a command output or paste a piece of text into a unix pipe. Fortunately, there are handy commands to do it.