Boot screens, Boot picker screen, works with firmware updates and has Audio out in Mojave and Catalina.
You'll soon be able to put the same card in your 2008-2012 Mac Pro that comes in the new $6,000.00 monster from Cupertino.
Stay tuned for Vega news.
Caveat #1: 3,1 will boot, it is up to you to patch SSE4 libraries, etc. The EFI works, rest up to you.
UPDATE: To clarify, these cards are 95% done. Will be offering 580s for pre-order as soon as I remember how to add a product to the website. US MVC will be shipping within 2 weeks, barring any roadblocks .I believe our European partners will be onboard as well.