WordPress Custom Payment Gateway Integration

I need a payment gateway integrated into my WordPress site using custom code.

It will be for this page and needs to prompt a membership sign up for people to read the stories: https://newhumansofaustralia.org/stories/

Requirements:
- Support for multiple currencies
- Custom code integration

Ideal Skills and Experience:
- Proficiency in WordPress development
- Experience with payment gateways (e.g., PayPal, Stripe, Square)
- Strong coding skills (PHP, JavaScript, etc.)
- Familiarity with multi-currency transactions

Please provide examples of previous work and relevant experience.