One domain name, two dirs or subdomains.
One admin, in admin setup 2nd shop (like opencart, which is way to buggy to use)
Select which cats and products to show on each site
Select which info pages and blocks to show on each site
Customer can switch between the 2 sites during shopping then checkout on either, cart is shared.
It’s a little hard to understand the model you have.
Using 1 cart for multiple sites is easily done
(I can’t elaborate or I’ll get dinged for self promo)
But I wonder if you really want to follow the path
you’re discussing as I see the success trend following
the folks that separate their product lines to provide a
more laser focused site versus a “more items” site.
Again … it’s hard to understand the model so I might
be way off base here.