Connect Existing Price Simulator to WooCommerce personalised Checkout with Payment Integration

I’m looking for a skilled WordPress/WooCommerce developer to connect an existing custom price simulator to a personalized checkout page and ensure full payment processing using my custom payment gateway.

What’s Already Done:
A fully functional HTML/JS price simulator is ready.

A custom 2-step checkout page is already developed.

The payment gateway API is available and documented.

What I Need:
When a user finishes using the price simulator, the calculated total should be passed to WooCommerce and added as a product or custom order.

The user is then redirected to the custom checkout page, where the process continues.

The checkout must complete the payment using the provided payment gateway API.

Ensure the whole process is smooth: simulator → custom checkout → payment → confirmation.

Requirements:
Experience with WooCommerce custom flows and checkout customization.

Ability to handle frontend-to-backend integration.

Strong skills in API integration and working with custom HTML/JS code inside WordPress.

This is a focused task — the core work is connecting the logic between the existing simulator, WooCommerce, and the custom checkout.

Please apply with relevant experience or similar projects you've handled.