How to remove Snap completely without losing Firefox?

I am wondering whether or not there is a way to completely remove Snap from Ubuntu 21.10 (Impish Indri) without losing the ability to install Ubuntu's default browser Firefox.

When I just recently updated to the newest Ubuntu release I realized that the installer programmatically reinstalled Snap, although I had manually removed it before. Additionally the installer removed Firefox, which was installed via the repositories, and reinstalled it via snap.

As I don't want snap to be installed on my machines for various reasons, my question is: Is there a safe way to remove it, and to get the Firefox DEB back to the sources?

Is there a PPA? Could I use a source of an Ubuntu flavor additionally, which didn't remove the Firefox Deb from its sources?

You can combine two measures.

Start by removing Snap package of Firefox by snap remove firefox --purge.

Then follow the steps:

1. prevent Snap installation by purging and pinning it with negative priority:

   sudo apt-get autopurge snapd
   
   cat <<EOF | sudo tee /etc/apt/preferences.d/nosnap.pref
   # To prevent repository packages from triggering the installation of Snap,
   # this file forbids snapd from being installed by APT.
   # For more information: https://linuxmint-user-guide.readthedocs.io/en/latest/snap.html
   
   Package: snapd
   Pin: release a=*
   Pin-Priority: -10
   EOF
   

2. Then install Firefox from

   • official repositories as simple as

     sudo apt-get install firefox
     

   • some third-party (but trusted) repositories

     a. deb-packaged Firefox from UbuntuZilla - regular or ESR
     Add UbuntuZilla repository with its signing key by

     echo "deb http://downloads.sourceforge.net/project/ubuntuzilla/mozilla/apt all main" | sudo tee -a /etc/apt/sources.list.d/ubuntuzilla.list > /dev/null
     sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 2667CA5C
     sudo apt-get update
     sudo apt-get install firefox-mozilla-build
     

     Note: if one needs ESR version - then replace last command with sudo apt-get install firefox-esr-mozilla-build.

     Removal is possible by the following commands:

     sudo rm /etc/apt/sources.list.d/ubuntuzilla.list
     sudo apt-get autoremove --purge '*firefox*'
     sudo apt-get update
     

     b. deb packaged Firefox ESR version from Mozilla Team PPA

     To get Firefox ESR version installed from Mozilla Team PPA use commands below:

     sudo add-apt-repository ppa:mozillateam/ppa
     sudo apt-get update
     sudo apt-get install firefox-esr
     

     Additional locales may be installed by using packages like firefox-esr-locale-it (example for Italian).

     To remove deb-packaged Firefox one can use commands like:

     sudo apt-get install ppa-purge
     sudo ppa-purge ppa:mozillateam/ppa
     sudo apt-get autoremove --purge
     

   • Locally extracted Firefox archive

     If one needs to download and install Firefox to the home folder, then it is possible in the following way:

     mkdir ~/Software ~/bin
     cd ~/Software
     wget -c http://ftp.mozilla.org/pub/firefox/releases/93.0/linux-x86_64/en-US/firefox-93.0.tar.bz2
     tar -xf firefox-93.0.tar.bz2
     ln -sf /home/$USER/Software/firefox/firefox ~/bin/firefox
     
     # create desktop-file with long command below
     mkdir -p ~/.local/share/applications/
     cat <<EOF >  ~/.local/share/applications/firefox-user.desktop
     #!/usr/bin/env xdg-open
     [Desktop Entry]
     Encoding=UTF-8
     Name=Firefox (local)
     GenericName=Browser
     Comment=Web Browser
     Exec=firefox %u
     Icon=/home/$USER/Software/firefox/browser/chrome/icons/default/default48.png
     Terminal=false
     X-MultipleArgs=false
     StartupWMClass=Firefox
     Type=Application
     Categories=Network;WebBrowser;
     MimeType=text/html;text/xml;application/xhtml+xml;application/xml;application/rss+xml;application/rdf+xml;image/gif;image/jpeg;image/png;x-scheme-handler/http;x-scheme-handler/https;x-scheme-handler/ftp;x-scheme-handler/chrome;video/webm;application/x-xpinstall;
     EOF
     
     update-menus
     

     then logout and login back.

     To remove such local installation use commands below:

     rm -rf ~/Software/firefox
     rm -v ~/.local/share/applications/firefox-user.desktop
     rm -v ~/bin/firefox
     update-menus
     

Discussion and notes:

My personal choice will be one of deb-based.
I would prefer ESR (2b) to get my Firefox behavior stable as it is needed for enterprise level application.