This guide includes the macOS Catalina installation and the EFI file for Clevo N850. You can use it especially to solve the graphics card problems after the installation. The EFI file is fully compatible with macOS Mojave and Catalina.
macOS Catalina v10.15.3 download link: macOS_Catalina_v10.15.3
Clevo N850 EFI (Monster Abra A5 V9.2) download link : clevo_n850_efi