That's also the solution I use. Especially because I have multi-rows set up in Firefox and each update breaks this.

Plus, when installing the binaries manually, you can also apply some "hidden" settings by creating a distribution/policies.json file inside the firefox installation folder. This is what mine contains:

  {
    "policies": {
      "DisableAppUpdate": true,
      "DisableFeedbackCommands": true,
      "DisableFirefoxAccounts": true,
      "DisableFirefoxStudies": true,
      "DisablePocket": true,
      "DisableSetDesktopBackground": true,
      "DisableTelemetry": true,
      "NoDefaultBookmarks": true
    }
  }

It's kinda sad how many settings you have to configure not only here in order to not be nagged constantly. It's like you are fighting against your tools.