Checkout shell
Final payment should be focused, official, and easy to finish on mobile.
The product page can stay expressive, but checkout should become narrower and calmer. This keeps the user on one job at a time: contact details, shipping information, then payment.
Pressure-safe rule
Any future smart downgrade for product-page quick pay must not interfere with cart or checkout payment components.
Checkout status
Your checkout is waiting for a cart.
Keep this state simple and recoverable so shoppers do not land on a dead-end form after moving too quickly through the flow.