This is a first Gatsby site.
For this project I purchased this Adventures' template on Theme Forest.
I converted all the necessary HTML into JSX and used the existing styling that came with the template. I did some customizations with standard CSS but mostly through Styled Components.
All the Javascript/Jquery logic had to be replaced with ReactJS logic.
The contact form logic is hosted on AWS. I used the Serverless Framework in combination with AWS's Lambda and EMS service. This is the tutorial I followed: Building A Serverless Contact Form For Your Static Site.
The site has a headless CMS, in particular Netlify CMS. For this, I followed the docs on Gatsby's site: Sourcing from Netlify CMS.
The site is hosted for free in Netlify. Kudos to these guys.