Shopify Checkout Form Integration

I need a Shopify app built specifically to enhance the checkout flow. The core goal is simple: inject a custom order-form right into checkout so I can collect extra information that the standard Shopify fields don’t capture.

Here is what I’m after:
• A checkout-focused app (embedded or extension) that adds my custom order form seamlessly on the final step.
• Form data must be stored with the order record and surfaced in the admin and in the Order API response.
• The solution must respect Shopify’s latest Checkout Extensibility requirements and pass app store approval.

I’m open to complementary features such as guest or one-click checkout support if they fit naturally, but the form integration is non-negotiable. Clean code, clear documentation, and a quick test store demo will be part of the acceptance criteria.