My question is pretty straightforward: since you can force a job to run on a specific node, is it possible to disable preemption on a given node ?
Like, if I force a pod to execute on that node I know for sure that it won't get preempted ?
...is it possible to disable preemption on a given node
No, pod preemption doesn't apply at worker node level. Instead, define a priority class with preemptionPolicy: Never, then use this class in your pod spec priorityClassName: <the top priority class that you defined>.