CIDLib VS cmake-init-executable

It's open source. It's in two parts CIDLib, which is the general purpose layer: https://github.com/DeanRoddey/CIDLib/

Then you can pass this to the configure command using the --toolchain flag. If you keep the embedded specific details far far far away from your CMakeLists files, then you get an otherwise completely normal CMake project that supports building for the host platform as well. This comes with the benefit that you can write the business logic in a separate object library target, which tests can consume and run on the host. You can see that in action here: https://github.com/friendlyanon/cmake-init-executable

You can take a look at an example workflow with CMake using presets here.

This example is similar to what you need in structure sans the executable at the top level.

Besides, a CMake project that focuses only on building something doesn't need more than a CML file. If you compare the baseline with a fully populated cmake folder (https://github.com/friendlyanon/cmake-init-executable) and this one https://github.com/friendlyanon/generate-opaque-structs then you can see that you don't need anything from the baseline, but it's all very useful stuff that everyone should use.

You make the entrypoint as minimal as possible and develop the actual application logic basically as a library. This example - while being C++ - shows you how to do that. You can generate the exact same project with the tool linked in the README with the --c switch for a C project.

Ah, you mean flashing as in download. You can create a custom target for that, like in this example. Do note that the example allows complete customizability of the commands, because the developer environment isn't necessarily identical for everyone.

You create separate install components for them and then you can control how those components are packed using CPACK_INSTALL_CMAKE_PROJECTS.