DRM in DragonFly has been updated to match Linux vers. 4.20.17. See the commit message for the newly-supported video chipsets.
I waited to post this cause there’s a few setup details that may or may not affect you when you try it.
A running description of activity related to DragonFly BSD.
Moreover, servik has been working hard on fixing hardware acceleration for amdgpu, and he’s almost there. We’ll soon have accelerated amdgpu for Picasso (e.g., RX550, RX580) and Raven Ridge (e.g., 2400G).