I ran a team that provided “engine” code (C++) for native apps (on a couple of platforms) for decades.

Same here. The best approach I’ve seen is code is 80-95% C++ business logic, plus a small platform-specific GUI shim in the native language to keep the nice platform look and feel. All the major PC and mobile platforms still can call into and out of C and C++. This is the way! It has been tried and true for years.