My only qualms is the number of genuine C only compilers in use, vs number of embedded system companies/projects/codebases in the world.

The subset of C features that are incompatible with C++ is quite small, and most of the features are a little out of the way IMO.

Of the regular suspects (GCC, MSVC, Clang), your C codebase is probably entirely compatible with C++ as each of these has varying levels of compliance with the C and C++ standard.

> Of the regular suspects (GCC, MSVC, Clang), your C codebase is probably entirely compatible with C++ as each of these has varying levels of compliance with the C and C++ standard.

yep, leave it up to the technical crowd to try and split hairs too fine.