I also confirm the use of the Blackbird video, up to Kernel 5.4 on Ubuntu there is no support for the Radeon 5700 from what I know. But more generally I remember that support for Navi 10 was introduced from Kernel 5.6 onwards so with 5.4 we still have integrated video. I tried to use Ubuntu 20.10 with Kernel 5.8 but unfortunately also in this case as on Debian and as on Fedora, starting the operating system, everything crashes and you have to restart the whole computer ... Returning to Wayland, I confirm that it does not even work with video integrated to the graphics card, it only works under Xorg ...