If it is C++ I wouldn't think about python in most cases. Rust should come to mind. Ada, or D are other options you sometimes hear about.

Is it possible to integrate any of those while allowing seamless debugging? IE, step right from one into another? I've yet to see that happen.

If nothing else my C++ debugger will see the functions of everything in Rust, D, or ada - it might be a mangled name but generally I can figure them out. Once you step into python the debugger is going to see the python runtime functions and you need to dig into them to figure out what of your functions you are running.

I have yet to figure out how to get any language other than C++ into my system so I can't say how well it works in the real world. Then again I work on an embedded system with real time controls so I can rarely use a debugger since as soon as I hit a breakpoints all my must happen at time X functions fail to run and the whole system fails in a few ms.