Edge of Extinction (2020) on Netflix

Plot summary

The nuclear winter that followed World War III has lifted, but fifteen years after the war humanity is close to dying out. Organized society is gone. Food is scarce, and most of those still alive take what they need by stealing and killing; gangs and scattered individuals plunder what is left, and some of them eat the people they catch. A boy holds on alone in the countryside of southern Britain, where his survival depends on keeping away from other humans. That isolation ends when he crosses paths with a group of survivors, and with an enemy whose savagery none of them can imagine.