What happens if your GPU is NOT metal compatible?

I was getting ready for the Mojave update, then I read this:

https://www.pro-tools-expert.com/production-expert-1/2018/6/12/how-do-you-find-mojave-compatible-graphics-cards-for-cheese-grater-apple-mac-pro-51-computers

I've got the 5770 Radeon.

Do I have to use metal? Is metal used in ARKit 2?

I'm mainly using the machine for iOS development and just need to run the latest version of Xcode.