Interesting!
I’ve ordered some noctua 5V fans to try this out myself. I take the existing 4-pin connectors in the pironman 5 max case do not allow for PWM control? (even though it seems they have 4 pins and they are populated?). I was wondering since I have a third fan (see Problem with 2xNVMe HAT in Pironman 5 MAX ) that is also the same fan you are using, a noctua 4cmx1cm 5V that I am using to cool off the two NVME drives that I had to put on top of the pironman 5 max case, in another powered HAT, since the internal HAT provided by the case could not handle my two NVMe drives). This fan is connected to one of the USB 2.0 ports. So I will “join” the two internal fans and will feed them to one of the internal fan connectors and will drive this upper fan to the other connector.
I wil modify –with your permission– your code so that the this third fan is PWM controlled by max temp of the two NVMe drives.
Will post progress!