Can’t we implement this ourselves without requiring upstream?
Create a wrapper that reads from /etc/wrapper.d/ and have wrapper_pre (for commands to be added before the actual program) and wrapper_post (for commands to be added after) variables based on the contents of the files there so you have:
${wrapper_pre}${program_name}${wrapper_post}
Create symlinks to run the program with our stackable wrapper by default and configure the program via wrapper.d.
So the program has one, configurable wrapper that wraps the program with other wrappers.