C# Separate Online Store into Different Solutions and Nugets

I am creating an Online Shopping Cart store. It is built through Net MVC Core.

There is a Front End View website: html, css, razor.

Then we have backend code design for Customers: including shopping cart, searching, buying orders, submitting orders.

Finally, there is backend for Vendors: vendors can submit their inventory, Products, and Supply Quantities which will be sent to online shopping place. This can be done with API calls or Flat files.

Currently everything is in 1 Solution. Is there any generally recommended practice for splitting into different solutions, or should I refrain? Should I separate the Customer Backend from Vendor backend? What is the general practice for different solutions and Nuget packages? I just started learning C#, and looking for basic guidelines, not sure where to start. Perhaps there is different flavors/methods of doing this.