Showing other shops, items etc on a Homepage?

Hi Guys.

I am hoping you can point me in the right direction.

So i am 90% finished on my theme on my multisite website and the i am wanting to have my own page to show products / shop items from every other shop randomly and automatically. Is this possible? I don’t really know how people will know the other shops on their and advertise their products without this?

Any help on this would be a huge, huge help.

Example:

So my main site homepage at the moment is showing a register page. But instead i would like it to be like etsy which will show items or even if its just the shops which are on there. So people will see examples of what my site is about and again to advertise for people.

Thanks.