By the time the kernel panics the OS has been effectively shutdown so no damage and/or corruption will occur. The bigger downside of gpio-poweroff is that you can no longer wake the Pi via GPIO 3 you have to use the run pin instead (or, maybe, global-en on a 4B).
Have you tried any of the software Pimoroni provide via their github? https://github.com/pimoroni/fanshim-pyt ... service.sh
Or asking them for assistance?
A posible hardware hack. No idea if it's practicle with the fan shim:
- Disable console output to the serial port but leeave the serial port enabled.
- Modify the ground lead of the fan cable inserting a transistor between the fan and the board.
- Drive the transistor from the TX pin
The TX line is active low. It goes high on boot and low on shutdown
Attempts to contact me outside of these forums will be ignored unless signed in triplicate, sent in, sent back, queried, lost, found, subjected to public enquiry, lost again, and finally buried in soft peat for three months and recycled as firelighters