A new driver is available: Updated AMD Radeon Software for Linux 19.30 released
AMD has released an updated version of Radeon Software for Linux 19.30 with support for the Radeon RX 5500 Series. The new version also compatible with Ubuntu 18.04.3, RedHat Enterprise Linux 8.0, RedHat Enterprise Linux 7.6, CentOS 8.0, CentOS 7.6, and SLED/SLES 15 SP1.Read more @ Linux Compatible