The Dell OptiPlex 7000 SFF offers Wi-Fi and PCIe expansion

The OptiPlex 7000 SFF covers the basics. The wireless card is upgradeable via a standard M.2 2230 Key E slot, so you can swap in a newer Wi-Fi module without much fuss. There’s also a full-height PCIe x4 slot for expansion cards, which gives you room for a sound card, capture card, or extra networking.

It’s not a wide-open chassis, but the essentials are there. If you need more than that, you’re probably looking at the tower version.