Interactive Chat App with Meeting Scheduler -- 2

I'm looking for a chat application that enables users to schedule meetings directly from the website to any third-party app (Google Calendar, Zoom, Microsoft Teams) of their choice.

V.imp: I need a workinh prototype not fuly functional but good for demo purposes

Key Features:
- Text chat functionality with users
- Integration of any one third-party app for scheduling meetings
- Incorporation of a payment gateway (preferably RazorPay or UPI)

Ideal Skills & Experience:
- Proficient in web development with a focus on interactive applications
- Experience in integrating third-party APIs
- Prior work with chat application development
- Knowledge of and experience with payment gateway integration
- Familiarity with scheduling apps like Google Calendar, Zoom, Microsoft Teams

Include a simple login system for users.