Just to clarify, this requires both the client and the debugging script to be running 3.14? So I cannot have a script running an older version of Python but use a Python 3.14 debug script to attach to the running script?
If you want to "just" use sys.remote_exec, you will need to use that from a matching Python version. If you dive into the implementation (check out the PEP), you could most definitely write a C or Rust program that implements remote_exec and "does the thing".
The protocol is basically "tell the program to read a python script from this file". That python script will be executed in the running program's environment, but you don't need for the software on the other side to be a python program!
sys.remote_exec itself only targets same Python versions though.