Raspberry Pi 4G Proxy Server with GUI

Hello, I'm looking for someone who is able to help me develop a proxy server based on raspberry pi, and a software for control of the proxies, rotation period, authentication and user assignment for resale.

I have an example here in this video of what I'm looking for:
https://www.youtube.com/watch?v=SgNOsvCLnh4

I also expect from you the exact components needed to create a mini-server that can hold up to 40 4g dongles simultaneously. It doesn't have to be beautiful, it has to be functional for the backend to handle the sales of proxies.