Payment Gateway & Service Page Setup

I have a website, there is a work on Service page and need to integrate a payment gateway and google sheets for data collection, developer who can bring them to life and wire them to our in-house bank gateway (full API documentation will be provided). The page must allow visitors to book a paid consultation, start a recurring subscription, or make a one-time purchase, each flowing cleanly through the same gateway and returning the appropriate success or error states.

My priorities are:

• Integrate a payment gateway.
• Service page setup.
• Google Sheet setup.
• Test environment first, then production deployment, with written hand-off notes so my team can maintain it.

Please let me know the tech stack you prefer and any similar custom-gateway projects you have shipped. I will share the designs and API docs with you.