And you'd need to remember to not use autonomous part of microcontroller (like a timer output) to implement it.

Considering the connected net is named "tip_control" I'd assume its PWM that is fed into MOSFET controlling the heater... and in vast majority of cases that PWM will happily run when core is hanged.

Looking at datasheet of the microcontroller PA6 does indeed go to tip_control and one of alternate functions is TIMER2_CH0, and at least glancing at code

    /* enable TIMER1 - PWM control timing*/
    timer_enable(TIMER1);
    timer_enable(TIMER2);

https://github.com/Ralim/IronOS/blob/1fbcdcdf987a28541524e4f...

... timer_init(TIMER2, &timer_initpara);

    /* CH0 configuration in PWM mode0 */ 
    timer_channel_output_struct_para_init(&timer_ocintpara);
    timer_ocintpara.outputstate  = TIMER_CCX_ENABLE;
    timer_ocintpara.outputnstate = TIMER_CCXN_DISABLE;
    timer_ocintpara.ocpolarity   = TIMER_OC_POLARITY_HIGH;

they are using it for PWM. The watchdog itself also appears to be enabled tho, so there is a chance it will kill itself the normal way