Are there any Designers & developers, who would custom design an ecommerce website template and then map it to Magento 2.1 or 2.2?

yes , I can map custom design in to magento 2 or 2.1. another option is to install custom themes which makes the work more easier

I did´t understand 100% your question, but I would notice that Magento is almost a complete e-commerce solution with hundreds of templates available online. I tried it before just for testing.