Add a Bookmark icon to Firefox search bar

It's quite simple.

First right-click on the Pocket icon and select 'Remove from Address Bar'. Then click the 'page actions' (three dots) icon, right-click on 'Bookmark This Page', and select 'Add to Address Bar'.

You can do the same (i.e. add/remove) with other actions that the 'page actions' list provides.

I'm on Firefox 64 (and you'll be as well once you update).

For Pocket, I have

extensions.pocket.enabled;false

in my about:config. See https://askubuntu.com/a/1083166/248158 for how to do that (and other stuff) via a policy. Here are my policies:

{
  "policies": {
    "DisableFirefoxStudies": true,
    "DisablePocket": true,
    "DisableTelemetry": true,
    "DisableSetDesktopBackground": true
  }
}

Now, regarding the bookmarks. If I'm on a page which I haven't already bookmarked, I see a hollow star enclosed in red in the image below:

If the page is already bookmarked, the star is filled. Its color may depend on your gtk3 theme.

If you don't see the star at all, see if https://support.mozilla.org/en-US/questions/1203256 helps.