I have implemented a similar header in my native app.
For back button, I used an image of back arrow. Placed this image inside a container with some padding in container to increase the clickable area around image. Then I set the on click action of that container to close page.

For toggle menu, I used the widget “Pop-up menu”. Its part of native mobile resources package and I think this package is by default part of a new native app project. You can set an image to use as toggle menu button, and on click of that image, a menu will open. You can specify menu items for it. Below is link for details of this widget
https://docs.mendix.com/appstore/modules/native-mobile-resources#popup-menu