Having no payoff is the payoff. After everything that's happened to him, he is killed offscreen and his son, now an adult, doesn't even quite remember him.
The journey is the point, basically :) The scenes with the fellow "refugees" are great, insightful glimpses into Brasil, into that 1970s Brasil in particular. They don't need to lead anywhere in particular for me to enjoy it.
That being said, I did like Bacurau and Aquarius more than The Secret Agent. But that speaks more to how incredible those films are.
Fair enough if you enjoyed it. I'm no stranger to the period or the director's movies and still found this one overly contrived. The tense bits are so engaging that the fantastic/anachronistic felt like it detracted from a great story.