fetch and display data within multi-site enviroment

So instead of each site admin using the usual e-commerce back end to administer their site, you want them to use your root’s front end? I think that’s a lot more complicated than you imagine, so I would be gob-smacked if you were able to find a plugin that allowed that.

A better bet would be to re-style the WP back end so that it has the appearance you’re looking for, but works as usual for all site admins. I’m not sure how to do that, but finding a plugin that allows custom back end styling seems much more likely than your JSON-like box.

Thanks for reply @bcworkz.
I don’t mean the admin area. I need the front-ends of each site to be streamlined as such that user wont know the difference where I can place links from each site to one common area/site to display and post data. Hope that makes sense.

I think there may be a confusion of terms. I was thinking user as in individual site admins, but you mean user as in random visitor/customer to your domain, yes?

Then what’s the point of multi-site if the visitor will only interact with your root front end? I think there may be a better way to do this than multi-site, but I need to understand your site concept before suggesting an alternative. No judgment, just trying to understand.

Well, yes, I mean the visitor/customer. Each one of these e-commerce themes are stand-alone products which I’m trying to utilize them under one umbrella. I figured, the end-user doesn’t need to know that, which is why I want to create a front-end that enables end-users to interact with one theme.
Utilizing multi-site works well just as long as I can get the front-end unified somehow. Hope I was able to explain it clearly. Thanks again for taking the time.

I think I get it. Why couldn’t all of the sites simply use the one theme?

Are you(or a single client) managing all of these sites/products or are there other merchants involved on each site? If it’s all you/your client, why couldn’t you use a hierarchal category structure? Each site’s product could instead be assigned a top level category. Any query for that category would result in a particular category template being used, just as a separate site is used now. Any site categories used would then fall under this parent so there is no crossover.

If necessary you could even prevent general queries without a category to reinforce the concept of separate sites. After all, it’s all just semantics. Semantics matter to us humans, but not computers. They don’t care how things are divided and assigned, as long as they are. It’s not that difficult for categories to appear as separate sites. Considering you wish them to appear unified…

Just some thoughts since using multi-site for this just doesn’t ring true for me.

Back to your original question. There’s no such magic JSON box, however all the site’s data does exist in the one DB, so you could in theory directly query all the different site tables as needed. Doing so would involve some rather complex custom code I think. The various sites are truly separate and combining them in root would not be simple.