Conceptually it is similar to replace malloc using LD_PRELOAD or LD_LIBRARY_PATH manipulation.  When I cannot modify the executable/library binaries, this allows replacing the functionality of specific functions.

If we could assign a specific (persistent) task group to all asyncio tasks spawned by a black-box code (when the black-box itself does not use task groups), we could achieve the full application-level transparency on the timing of task cancellation.