Develop a module for integrating Wordpress with a payment system

There is TK. There is a team lead who will help. It is necessary to make an application with a complex logic for accepting payments. It is the application that is not easy to connect a ready-made plugin like Robokassa. We need a specialist with good experience of Backend, we need experience with WordPress. And it is important to have time and the opportunity to start work in the near future. Next, a constant stream of jobs is assumed.