What are the nuances of such an approach?

Question

Search Engine Optimization

I don’t really rummage in promotion, so I decided to ask the pros.
There is a store that sells accessories for mobile electronics (mainly for apple) and is mainly aimed only at its region. If you make a landing page on the main domain (with certain selections of products), and put the main store on the subdomain, what problems can there be with further promotion?
PS There is no site yet, that's why I'm asking.

Answer 1

Why not vice versa?
On the main store, on third-level domains there are landing pages for goods and promotions. Google loves its third domains.