Ah cool. Yes, Xcode is always a bit flaky with SPM. Just want to point out that Xcode 14 is only required for the build plugin. (and this was a new WWDC 2022 feature in Xcode, hence the requirement, it may work with earlier SPM builds.)
The tech itself works for anything Swift 5+ I think.
I think it is save to assume that plugins (and dependencies) are built and run for the host platform (which may very well be different to the target platform).
This is a little different to other cross compilation issues.
What other issues do you have?