This message was posted on behalf of Intel Corporation
The Computer Manufacturer Support is the best resource to confirm which adapters are compatible with your computer. We strongly advise to have wireless adapters replaced with the OEM's Authorized Service Provider whenever possible.
An incompatible adapter may not be recognized, cause errors, connectivity issues, or even hardware damage. For more information, please check the following advisories:
Why Doesn't My Laptop Recognize My New Intel® Wireless Adapter?
Regulatory Information Regarding Hardware Installation or Upgrade
It is important to mention that you should check with Dell Support if they recommend using your computer with Windows® 10.
Having said this, Intel has made different adapters supported with Windows 10, as noted in the document: Supported Operating Systems for Intel® Wireless Products
Current adapters use M.2 form factor, however, some older models, such as the Intel® Dual Band Wireless-AC 7260 were also available in PCIe Half Mini Card form factor. You can check with Dell about this option, or any other that suits your needs.