I am no Nietzsche expert so I defer to your definition of truth, which I think is very closely linked with whether you subscribe to the Copenhagen intepretation/wave function collapse in quantum mechanics.
My stand on free will is that it doesn’t exist because all actions are shaped by the environments. To bring this back to RL — I think that humans function as deterministic neural nets within a specific wave function collapse. If human brains are stochastic neural nets, then ‘free will’ exists only in the sense that this stochasticity leads to different, random outcomes which cause a branching in the Level III multiverse. Time will tell, but my sense is that RL and machine intelligence in general will end up mimicking this ..ahem..model.
I agree that that the illusion of free will is good for life — but, I think the word ‘illusion’ can be misinterpreted here to seem almost magical, but I think of the word in the same context as ‘time is an illusion’.
This is where it gets rather dopey — this conversation should be moved to a pub!