i have a separate build-flow that can produce .out files for the MT3620/M4 core using the same gcc-arm compiler.... for reasons beyond the scope of this question, it's not practical for me to migrate this build-flow into cmake....
once i generate the .out file, my thinking was to simply envelop it within a project structure identical to the samples -- with an conforming app_manifest.json file.... from here, i could effectively run just the final step of the cmake build -- which generates the image package....
before i go down this path, is there anything obvious i'm missing here????