Yes there is. It will be in the list of icons when you click on "+Customize" in the Firefox Menu. Just drag it back.

You're wrong. The only button you can add is "Save to pocket" this button does not allow you to view your list.

That list will work if you are logged into Firefox Sync. For example if you click on the button on an open page it will say "Saved" and underneath there is "Remove Page" and "View List" View List takes you to https://getpocket.com/a/?src=ff_ext_saved

Technically you're right you can get to your list from that button. However, you can't pull up your list from that button without saving the page you're on. Also, it loads the full webpage version of the list. That's horribly slow compared to the old Add-on that would cache just the URLs and txt title of your items. If you had added items to your list from another device there was a refresh button in the dropdown that would update the list in a fraction of a second. Now I have to wait 8-10 seconds for the stupid webpage to load.

So the answer to my question is really, no there is no way to get the same functionality the old add-on had with the new built-in Pocket. IMHO, the built-in Pocket is a step backwards from the old Add-in and is inconvenient enough to make the service no longer worth using.