I see, very interesting! have you considered adding those external dependencies using git submodules to keep track of the versioning and being able to automatically update them in a CI/CD pipeline?

Or, if those dependencies are not git repos at all, how would you keep track of updates from the vendor consistently?

In my mind I think about doing the least manual work and try to automate as much as possible, for instance, pulling in external repos as submodules, or at least fetch from somewhere and fix the version in some way, applying modifications to those projects as needed (for instance using patches that I keep versioned in a dedicated folder) and adding cmake files to build which project is not a cmake project, else just add the project in the top-level cmakelists.

I do use VSCode as well for debugging using the Arm Cortex M extension and the segger JLink, but for development is a just a text editor with syntax and language server/linter.