since it wouldn’t be swift if you weren’t holding it wrong, i have learned that swift binaries are just like any other type of binary and they search for libraries in the same directory that the toolchain lived in at the time when the binary was originally compiled.
in this thread i managed to compile with a dynamic standard library on a separate machine from the deployment target, by recreating the directory structure of the target machine.
it’s annoying, but at least we have a solution/workaround for it, which is more than can be said for a lot of other problems in this space