Pop put is banner sliding in and out on the side of the page comparing to pop up which pop ups and annoyingly blocking user from interaction with the page. You can visit https://www.elvistudio.ee/collections/all-photographs and scroll to the bottom and you will see pop out in the bottom left.
I checked SumoMe and they call it Scroll Box for example.
Aha! That's what you call pop out. It isn't its conventional name)
Try wisepops. Their popups support such behaviour.
Adding to Shopify should be easy:
Just click on the Shopify connect button in our "get embedded code" on your WisePops dashboard.
Then you can build it yourself :) Check out my post on this same topic: http://99rabbits.com/bounce-exchange-alternative/ Maybe you'll find something useful.