- How do I declare Requires on my runtime dependencies from another module?
No changes on the RPM level. You also have dependencies on the module level, which makes their packages available to you. At buildtime it means their packages are available for you to install in the buildroot, at runtime that they are available as installable deps. Besides ensuring you depend on the modules that provide your packages in the appropriate situations, you don't need to do anything.
Isn't this what comps are designed for? # dnf group install $name