Hi Bee and welcome!
I’m using google gyp, (generate your project) which creates for me the Xcode project, and ninja build file to cross-compile for daisy seed. The whole is packaged in a meta-build-system python module to make it easy to use.
The project is here, it’s open source. Watch for the CI workflow files in .github to see how the machine is installed depending on the platform (it does not link properly using ninja on Windows yet).
Have a look at the test project to see how it is organised. The configuration (the equivalent to the projucer document) is the test.gyp file.
I’m planning to add VSCode/PlatformIO support, but if you are looking for editing from within Xcode and configure/build/deploy from the command line, that could be a starting point.
Hope this helps,
Raphael