stock-micron-rx570.rom @
https://ufile.io/yjdb4 (this is from MSI RX 570 4G Micron)
If you edit the bios manually and need to fix the checksum, you can load a Polaris rom in Hawaiireader (it will say unsupported rom), and then click save and it will just fix the checksum.
I loaded the stock-micron-rx570.rom above, and just changed core and mem clocks, no strap edits, and saved in PBE. Ubuntu kernel panics resulted. Had to reflash to stock, and then manually edit and fix checksum.