Hello
I am top 3% here with the skill and I have much experience of it.
I've reviewed your project description for a while.
I can work of theme customize, other apps integration and functions extend more, web page building(Shogun, Page Builder), webhook and other third party API integration work.
I am one of the few designers here that are not only able to design responsive (mobile-friendly) interfaces and website layouts but also execute the designs with coding to create fully functional frontend design following the best standards and practices.
Can we discuss more in details?
Thank you.