Seeing this came up in a previous discussion/thread, I thought I would share what I found and have been using to heat soak the chamber on my Voron 2.4r2 300mm build.
Must say, still have not achieved putting a heat soak parameter in the Start_print macro with success, but I will keep trying. I have a summary of the thread that I attached as a .txt file for this interested.
This is from the Klipper Discord group:
https://klipper.discourse.group/t/interruptible-heat-soak/1552
I include garethky's repository and Klipper configuration as acknowledgement of his work and is at:
https://github.com/garethky/klipper-voron2.4-config
Statement: I do not know the author or have any affiliation with the author.
Hope this may be of use to someone.
Interuptible Heat soak.txt