I was using Sierra for a year on my legacy system with Chameleon bootloader. (For same reason Clover UEFI not working on my hardware)
Intel Core i3 3rd Generation Processor.
Asus 710 2GB graphics Card.
Gigabyte H61 Motherboard
Samsung 320 GB HDD.
(I know this is pretty much old hardware but I don't need Mac for Video Editing and other tasks).
When you released Mojave, I directly install on same drive which have working sierra. Only just unchecked option to install Clover UEFI bootloader during Configuration.
To the surprise everything working out of box. (Graphics, Audio, Ethernet)