Need advice on website and app development?

Question

Mobile development

The task is as follows: to develop a website (+ application). The topic is the paid help of a psychologist. (I’ll say right away there are sites on which psychologists sit, register and sell their services via Skype and Whatsapp, but for them it’s inconvenient, as they themselves say, I would like there to be a service in which everything is already available with a judicial and understandable interface )
We need three packages of services: help in analog chat, voice chat, video chat, everyone has their own price: for example, analog 2 rubles / min, voice 3 rubles / min, video 5 rubles / min.
Doctor psychologist earns (he has his own personal account)
The client solves the problem, chooses a doctor for himself, chooses a package and away we go.
Well, if, roughly speaking, like a webcam, but not for jerks)
Please advise how easier it is to implement this project?
Thanks in advance to everyone