How to model inventory and products for manufacturer/retailer

I'm looking for some conceptual advice on database design and modeling in my Laravel project. I work for a manufacturer of portable buildings and metal roofing supplies. We sell products in 3 different ways:

1. buy and resale
2. manufacture metal roofing panels and trim (one stage production process)
3. manufacture portable buildings (4 stage production process)

I'm creating a custom, multivendor ecommerce and sales/MRP system with Laravel (I know... it's a mouthful). We are leaving Quickbooks where everything is an item in the system, whether it be a product, service, supplies, inventory, etc, etc. I'm trying to figure out if this is the best way to set up our database or if I should separate inventory from products, and also, how to set up variations and attributes properly. We have bills of materials for our portable buildings, and they also have configurable options. I'm trying to decide if I should try Aimeos or if I should pursue the fully custom route. If custom, can anyone recommend any existing web apps using Laravel that I might be able to look at to glean design patterns and make some decisions? I am a web designer with some limited knowledge of PHP and databases. I know a development company that I can work with to accomplish this, I just need some general advice (and would like to get as much done as possible myself) before I give them a scope of this project. This one part of the system is the big hang up for me right now, so any advice anyone may have will be greatly appreciated.

My current Laravel version is 9.51 and I have Filament installed. I plan on upgrading to v10.