Hello,
The costs of developing such a module represent from 32x to 140x the price of one year of your software, without any guarantee of compatibility with future versions of Hikashop! It is therefore logical that nobody starts.
Hikashop is already developed, and you are also paying for the support and compatibility with future versions of Joomla. However, developing another plugin from scratch will require time but we generally assure the compatibility with future versions of Hikashop if the customer allow us which is generally the case.
Also, 32 to 140 x the price of Hikashop seems a little bit too much.
Postfinance offers a new solution that has the advantage of solving the payment problem with TWINT
Thank you for your feedback, we'll keep that in mind and try to add it on our todo list !
Kind regards,
Mohamed.