Switching cards is not a problem and any vendor (Nvidia, AMD, etc.) or model is OK. What you do need to watch is the power requirements and cables. Some require more or different power cables. You have to find out what those were, and then possibly buy splitters or additional cables. Also, check the space. There is a limit depending on XPS model how far back a card can go. Dell usually gets its video cards from select vendors. They may not use Retail versions. I have an 8940 and my Nvidia RTX2060 I got with the Dell is NOT the same as the Retail version physically. I have one large fan vs. 2 smaller ones on the Retail card. It might also be shorter I think? I suggest getting the new card from a place that doesn't have a return or stocking fee (like Amazon) just in case you can't install it for any reason.
I currently have a NVIDIA GeForce GTX 1050 Ti in my XPS 8930. I looking to upgrade to probably a GTX 1070 or 1080. My question is, does my new card also need to be from Nvidia, or is a different brand ok? Thanks. 
XPS 8930, video card upgrade questions