Here's why I would avoid buying that Yeston Card no matter what claims they make.
Look at all the 550s on Newegg.
https://www.newegg.com/p/pl?d=RX+550+
Not a single one has a VGA connection. There are no RX 560s that still have a VGA port.
In a Hackintosh the GPU port layout matters. If it's not reference for the card it's going to create trouble with your hack. After looking at that you ask what Vbios does it use ? Is that even going to work if it's really a Polaris 21 card ?
Don't buy this to use with macOS. Windows 10 should have no problems with it.
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The only 550 that might work would be MSI branded and be using an RX 480 graphics core. I've not tested one or heard of anyone who has. If someone does please report back here whether or not it works.