There are out-of-bounds writes in the BLAS libraries for gfx803 GPUs (such as the RX 570). That hardware might work fine for your use case, but there's a lot of failures in the test suites.

I agree that the official support list is very conservative, but I wouldn't recommend pre-Vega GPUs for use with ROCm. Stick to gfx900 and newer, if you can.

The last time I checked, I was stuck with a pretty old kernel if I wanted to have the last version of ROCm available for my rx470. It's compatible at some point in time, but not kept compatible with recent kernels.

I don't buy it. Even running things like llama.cpp on my RX 570 via Vulkan crashes the entire system.