Thanks for the responses! I've been chugging away on my end to get things working.
As an experiment, I grabbed a USB stick (128gb) and compiled the source files on there. It was slow (~8 hours to compile from scratch) but worked! We will see how stable it will be. Of course, that doesn't alleviate the problem of swift-toolchain requiring a lot of storage to begin with.
@Max_Desiatov I've passed --release-debuginfo to build-script per the documentation here and see ~55gb build artifacts. It's quite possible there are more flags to reduce the artifact size, so I'll keep investigating! Definitely the lowest-cost path forward.
I found this thread which links to a YouTube video walking through the build system at a high level. Good viewing for anyone interested.
@johnno1962 Good to know! I'll have to dig deeper into this suggestion. Always love to hear interesting new dev tooling.
Will update with my findings when I find them.