I am looking for a specialist in the complete configuration of the online store module.

Sergey, I'll tell you a little about the current online store module in onebox (we also call it orange-shop).
Once upon a time, we decided to make a certain module that would be configured by "blocks", just like the OneBox interface. Made.
Later, problems that we did not even imagine climbed:
1. The idea of making a custom store in blocks so that it is adaptive makes the engine load 3 markups at once and then determine "what is the current screen size" on javascript and show the desired markup. This is bad for SEO, because we are forced to load 3 layouts in one page, Google will see three h1 headers, three content, and so on (I'm now conditionally).
2. OneBox's internal engine is designed to handle a huge amount of data, but it's not focused on "page speed".
I can’t say that everything is slow and stupid, but in the admin pages you can do various tricks to make it seem that everything works quickly (ajax elements, lazy-load, visual loading), which cannot be done for the pages of online stores - there either the server gives the page for 300ms, or does not give.
3. orange-shop is heavily supported. Clients want custom finishes, their own design, which does not develop the product in any way. If in OneBox 99% of improvements from customers immediately dig into the OneBox product, but this trick cannot be repeated with online stores. As a result, the product is not capitalized.
4. Over time, the understanding came that it is better to integrate CRM and IM not in one box, but in different ones, according to the "price sites / marketplaces" scheme. CRM uploads products and availability to IM, and IM uploads orders to CRM.
Given all three of the four, I said "stop sales and development of the orange-shop".
There are just a lot of companies that develop online stores, they do it cool, beautifully.
Companies that build accounting systems (CRM, ERP, BPM) are few.
And better OneBox will try to become the best in its niche than to fight hundreds of thousands of students who make an online store for $500. We just can't win in this market.
Therefore, in the long run, you are better off making an online store on some popular engine and integrating it with OneBox. It will be cheaper, work faster, less risk.