If they were ever tested/validated by Alienware, they would be listed here. As of today, they are not listed.

On Reddit and 3DMark you will find people who have used an RX 5000 Series card in an AGA for example

https://www.3dmark.com/spy/7795854

Just because their not in the list, doesn't mean they aren't working - just means they haven't been confirmed to be working by Dell... I've got my hopes up, since the Nvidia Series 3000 seems to have some issues.

 Well noted

Thanks mate.