I have been working with frameworks like backbone marionette, knockout and others... In those cases some times using handlebars or any other templating engine could be a good option.
When I am using Angular I found ng-repeat, ng-if and custom directives. Then I found Nunjucks that seems to be cool templating engine.
Is there any good reason to mix Angular with Nunjucks for a project? Is there any benefit on using both in the same project?
No. AngularJS' double binding will take care of any templating need you might have. Nunjucks is static while AngularJS is dynamic. With Nunjucks, you need to process you file to render pages.