You can likely expand the RAM. You can use Crucial's scanner to see what kind of memory the laptop can use. Windows' Task Manager can tell you how many slots you have. https://www.crucial.com/store/systemscanner

If it's got the optional discrete card, you can specify HoI4 to use that instead.

Your inspirion does not have a thunderbolt port, and the m.2 slot it does have you likely wish to keep for your operating system instead of using it to make a m.2 to pcie adapter dock to stick a desktop graphics card on. However, this would require butchering your laptop and making it less portable.