Yes, you can add an option fpm build --show-model-json (or toml, or whatever you prefer). Internally it’s just a simple printer of the model data structures.
You might find that fpm doesn’t put (print) everything in the “model”, in which case that’s a bug that we need to fix (just report it if you discover any issues). The idea is that the model (that you can print in any way you like) contains everything that fpm’s backend use to build the project, so by definition you can create a cmake and make backends, there is no other information that you need.