My RX570 I recently purchased works fine with Debian 9.
In order to get it work you will have to edit your sourcelist like so:
and add “contrib” and “non-free” to your mirrors.[/etc/apt/sources.list](https://i.redd.it/yv5aqykvvg721.png)
After that do
`apt-get install firmware-linux-free firmware-linux-nonfree`
You will need the amdgpu, but on a newer installation this should be already installed.
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