You can use the gallery widget for that, see https://docs.mendix.com/appstore/modules/gallery/
To get you started with a Custom widget, i made a small Expo Snack. https://snack.expo.dev/@juegoappteam/thoughtful-indigo-donut
check it on your phone directly by scanning the code.
Now the intention is to focus on the SocialPost component in the components folder. To this you need to page the post data which can come from the widget properties.
Check the pluggable widget documentation on how get the data from the mendix modeler to the widget.
Perhaps the first step is to simply get started with an blank widget with my code as sample and render a dummy widget and see how to shows :) then get on with other tasks 1 at a time :) you will get to the final results eventually.
All the best