I think if things had been set up properly, you ought to also have https://dl.cloudsmith.io/... in the list of repositories reported by apt-get update? 🤷‍♂️

In my Mint 21 the process goes forward but hangs with:

chmod: cannot access '/opt/balena-etcher-electron/chrome-sandbox': No such file or directory

so I create a symlink

cd /opt
sudo ln -s balenaEtcher/balena-etcher-electron

and then

sudo apt-get install --reinstall balena-etcher-electron

that completed without errors, but when I launch Balena nothing happens, it works only if I run

sudo ./balena-etcher-electron

i have the same problems, but then on my raspberry pi running debian bullseye.

jeroen@rpi4:~ $ curl -1sLf
'https://dl.cloudsmith.io/public/balena/etcher/setup.deb.sh'
| sudo -E bash
Executing the setup script for the 'balena/etcher' repository ...

OK: Checking for required executable 'curl' ...
OK: Checking for required executable 'apt-get' ...
OK: Detecting your OS distribution and release using system methods ...
^^^^: ... Detected/provided for your OS/distribution, version and architecture:

:
: ... distro=debian version=11 codename=bullseye arch=aarch64
:
OK: Checking for apt dependency 'apt-transport-https' ...
OK: Checking for apt dependency 'ca-certificates' ...
OK: Checking for apt dependency 'gnupg' ...
OK: Checking for apt signed-by key support ...
OK: Importing 'balena/etcher' repository GPG key ...
OK: Checking if upstream install config is OK ...
OK: Installing 'balena/etcher' repository via apt ...
OK: Updating apt repository metadata cache ...
OK: The repository has been installed successfully - You're ready to rock!

jeroen@rpi4:~ $ sudo apt install -y balena-etcher-electron
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
E: Unable to locate package balena-etcher-electron

Since our CI update the package name changed to balena-etcher (no electron at the end).
The balena-etcher-electron package is still available on cloudsmith with version 1.7.9, so it is unclear why is it not found.
If you want to install 1.13.1 you may try sudo apt install -y balena-etcher.
We will investigate and update the repo and docs accordingly.