See https://old.reddit.com/r/linux_gaming/comments/fddt2n/tutorial_how_to_use_amds_pro_vulkan_driver_or_the/
Arch Linux has a package: https://aur.archlinux.org/packages/vulkan-amdgpu-pro/
Direct download link: https://drivers.amd.com/drivers/linux/19.50/amdgpu-pro-19.50-967956-ubuntu-18.04.tar.xz