Hi,
When the HikaShop team develop a payment plugin, the quote include the fact that we will re-integrate the payment plugin in HikaShop afterwards (and continue supporting it, improve it, etc).
As far I could see for " synchrony financial" is that there is no available payment plugin for that platform, for HikaShop or other e-commerce solution we know.
If you have knowledge about integration documentation or existing plugin, it will help you to find a developer.
Because for the moment, it won't be possible for anyone to give you a quote for such plugin.
About the third party developers, we have a "commercial job" section in our forum and we also have a partner page.
www.hikashop.com/home/our-partners.html
Regards,