Hardened and personalized firefox `policies.json` file, meant to be placed in `/usr/lib/firefox/distribution/policies.json` or `/etc/firefox/policies/policies.json` on linux. See: https://firefox-admin-docs.mozilla.org/reference/policies/

policies.json

{
  "policies": {
    "DisableTelemetry": true,
    "DisableFirefoxAccounts": true,
    "DisableFirefoxStudies": true,
    "DisableFeedbackCommands": true,
    "DisableProfileImport": true,
    "HTTPSOnlyMode": "force_enabled",

    "EnableTrackingProtection": {
      "Value": true,
      "Locked": true,
      "Cryptomining": true,
      "Fingerprinting": true,
      "EmailTracking": true
    },
    
    "FirefoxHome": {
      "SponsoredTopSites": false,
      "Pocket": false,
      "SponsoredPocket": false,
      "SponsoredStories": false
    },

    "FirefoxSuggest": {
      "WebSuggestions": false,
      "SponsoredSuggestions": false,
      "ImproveSuggest": false
    },

    "OfferToSaveLogins": false,
    "PasswordManagerEnabled": false,

    "Preferences": {
      "signon.rememberSignons": {
        "Value": false,
        "Status": "locked"
      },

      "browser.newtabpage.activity-stream.telemetry": {
        "Value": false,
        "Status": "locked"
      },

      "browser.newtabpage.activity-stream.feeds.telemetry": {
        "Value": false,
        "Status": "locked"
      },

      "browser.search.suggest.enabled": {
        "Value": false,
        "Status": "locked"
      },

      "browser.urlbar.suggest.searches": {
        "Value": false,
        "Status": "locked"
      },

      "toolkit.telemetry.enabled": {
        "Value": false,
        "Status": "locked"
      },
      
      "ui.key.menuAccessKeyFocuses": {
        "Value": false,
        "Status": "locked"
      },
      
      "general.autoScroll": {
        "Value": true,
        "Status": "locked"
      },
      
      "browser.startup.page": {
        "Value": 3
      },
      
      "browser.sessionstore.resume_from_crash": {
        "Value": true
      }
    },

    "ExtensionSettings": {
      "*": {
        "installation_mode": "allowed"
      },

      "uBlock0@raymondhill.net": {
        "installation_mode": "force_installed",
        "install_url": "https://addons.mozilla.org/firefox/downloads/latest/ublock-origin/latest.xpi"
      },

      "{446900e4-71c2-419f-a6a7-df9c091e268b}": {
        "installation_mode": "force_installed",
        "install_url": "https://addons.mozilla.org/firefox/downloads/latest/bitwarden-password-manager/latest.xpi"
      },

      "jid1-ZAdIEUB7XOzOJw@jetpack": {
        "installation_mode": "force_installed",
        "install_url": "https://addons.mozilla.org/firefox/downloads/latest/duckduckgo-for-firefox/latest.xpi"
      },
      
      "sponsorBlocker@ajay.app": {
        "installation_mode": "force_installed",
        "install_url": "https://addons.mozilla.org/firefox/downloads/latest/sponsorblock/latest.xpi"
      },

      "{8c04d4c5-18cb-4185-bf56-34aa83fddd81}": {
        "installation_mode": "force_installed",
        "install_url": "https://addons.mozilla.org/firefox/downloads/file/4049847/keqing_card_genshin_impact-1.1.xpi"
      }
    }
  }
}

Summary of Features (introduced in same order as in JSON):

• Disables telemetry
• Disables Firefox Accounts integration (Sync) - (STIG)
• Disables studies (beta features, see STIG Viewer)
• Disables feedbackcommands (may be considered an attack vector with no user benefit)
• Disables profile import from other browsers or older firefox versions
• HTTPS only mode is enabled in all windows (Users may manually click through to proceed anyways)
• EnableTrackingProtection:
  • Settings to block cryptomining, fingerprinting, and email tracking are enabled and locked.
  • Currently Firefox interprets this policy by locking users onto the Custom protection profile.
  • Firefox also enables Cookies: Isolate cross-site cookies and Suspected fingerprinters: Only in private windows, but they are not locked.
  • Firefox does not enable Fix major site issues (recommended) nor Fix minor site issues, however they are not locked and users may enable them if they choose.
• Firefox home is minimalized, no longer showing stories or sponsored shortcuts.
• Firefox suggest will not show any internet suggestions (i.e. queries or websites you've never visited before).
• Firefox password manager is disabled as Bitwarden is preferable (and more secure).

Preferences:

• Further make sure that firefox does not offer to remember passwords, does not make any telemetry (NewTab settings are separate from the main DisableTelemetry setting), and does not show any search suggestions.
• The last four preferences are mostly personal preference/QoL:
  • Pressing the Alt key will no longer bring up the Menu Bar (instead you may right click the top bar and toggle it manually).
  • Autoscrolling (holding down middle mouse to scroll faster / more precisely) is enabled.
  • The value 3 means that firefox will restore previous session (rather than 1 which would show only a New Tab for the browser startup page).
  • Firefox will also resume previous session from crash.

Extensions:

• Users are allowed to install extensions
• uBlock, bitwarden, duckduckgo, and sponsorblock are installed by default as well as a nice theme.