On Ubuntu 21.10, dolphin-emu was accessible via a simple sudo apt install dolphin-emu. I didn't need to add a ppa or anything like that, despite Dolphin's official instructions. I suspect this is probably because it was available via Debian. edit it was available in Ubuntu 21.10 Universe repo, and not in Debian main

This no longer works in Ubuntu 22.04, and my existing dolphin-emu was removed when I upgraded. When I try to install it I'm met with this message.

Package dolphin-emu is not available, but is referred to by another package.

This may mean that the package is missing, has been obsoleted, or

is only available from another source

So clearly it was here, but the upgrade to 22.04 from 21.10 removed the binary from my system. The PPA also fails with this error

Hit:1 http://us.archive.ubuntu.com/ubuntu jammy InRelease

Get:2 http://us.archive.ubuntu.com/ubuntu jammy-updates InRelease [109 kB]

Hit:3 http://us.archive.ubuntu.com/ubuntu jammy-backports InRelease            

Get:4 http://security.ubuntu.com/ubuntu jammy-security InRelease [110 kB]

Ign:5 https://ppa.launchpadcontent.net/dolphin-emu/ppa/ubuntu jammy InRelease  

Err:6 https://ppa.launchpadcontent.net/dolphin-emu/ppa/ubuntu jammy Release

  404  Not Found [IP: 91.189.95.85 443]

Reading package lists... Done

E: The repository 'https://ppa.launchpadcontent.net/dolphin-emu/ppa/ubuntu jammy Release' does not have a Release file.

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.

So how is one expected to install dolphin-emu on Ubuntu 22.04?