About Unsupported GPU , what does Unsupported mean?

Hi. i just got a HD7850 GPU online , and for now i got rtx2060s on my system.

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while i'm waiting for my gpu , i am trying to prepare installation usb sticks first

so i followed the guide but stuck at some point.

before i asking for help about my issue , i thought i need to know it clearly first.

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which is

i know that this is unsupported GPU , but i wonder if 'unsupported' meaning that

1. You can't get into installation stage with it. even if the installation stick is properly made.

or

1. You can install osx with it but it is not gonna work smooth (accelaration etc.)

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