What slimsag wrote is correct. It makes cross-compiling code that needs to call C functions as easy a setting the GOOS and GOARCH and just building. This means no need to worry about building a C cross-compiler.
I do want to write an article about how purego works under the hood.
I don't have either. I was gonna figure out how to post it after I actually sat down and wrote it lol. I'll probably post it in the golang subreddit and maybe link to it in the README.md since it describes how purego works.
If memory serves, dev.to tends to be downranked or outright filtered by a bunch of places.
(I have no idea how or why that came about, I've merely observed people having all sorts of trouble getting posts on there visible in aggregators and etc.)
I do want to write an article about how purego works under the hood.