Thank you for your reply and advice, @Murazaki.
I hadn’t tried adding flags to my _.Target.cs yet (I didn’t know how to do that 
; thank you for showing me), but I wasn’t at a point yet to build my own code. I was still at step 5 of the Mac setup instruction in the README: building the ShaderCompileWorker.
That being said, I did add your code snippet to the ShaderCompileWorker.Target.cs and was able to successfully build the target!
I am building the UE5 target now – I’ll post here once I have the results of that.
Thanks!