Demo Abantecart there is a fast checkout in use and indeed that works with my webstore also. I just find it a mess. Without it there is this bug, at least in my shop.
There is a required field (red star) in shipping state (I think it's that in english). Default is "choose" and user can choose and continue. I think there is a bug because customer can leave the drop down menu to choose and continue. The result is that shipping is not calculated and is not even an option if it's leaved to "choose".
(It's in finnish "valitse" is "choose" and "alue" is "state)
This would be great. I use weight based shipping. At least in my case options means something extra to the product = weight increases. So now shipping is in some cases too low because of this.
Default stripe only support credit card payment but however Stripe supports many other payment methods so I think why they are not integrated to Abantecart. I have turned on Apple pay, Google pay, Klarna but in Abantecart Stipe stays the same, only credit card.
If someone is interested to help me out that would be great!