I learned a lot building https://sqwok.im and am currently building a brand new project using most of the same stack (use what you know!).

The project calls for a consumer mobile app with an administrative web app.

The stack:

- Cloudformation all the things (front/back/deploy/routing/etc)

- Python Starlette rest api

- Dynamodb

- Cognito (not using their web ui)

- Ember.js for the web app

- React-native for the mobile app

Using whatever tech you're familiar with is the best bet to getting a project off the ground quickly in my opinion.