What knowledge is needed to create such a product for android?

Question

Android

Have a nice day, everyone! Started doing android development on java. So that I always have a goal, I come up with a difficult task for myself - and I try to get the necessary knowledge and complete it. This motivates me a lot.
So this time, I came up with an awesome (as it seems to me now :D ) idea for myself, and wondered - what skills do I need to have in order to be able to do this?
Here is a rough description of what I want: an application where each user has his own page, you can write messages in a PM or in a general chat, there is a map of the city on which any places with photos are marked, there is also a certain database with certain photos /text available to everyone.
Here, I will be grateful if you point my training in the right direction :) (In the meantime, I will continue to study the necessary minimum)

Answer 1

You need to know how to write UI for android, what components the UI consists of, recommendations for visual design .
A list of restrictions that android imposes on the application (what permissions to ask for, for example, what operations are performed asynchronously). Which pattern to separate business logic from UI to choose.
- Where and how to store data (here you need a backend - this is not related to android).
- How will the application receive the data? (protocol of the application with the frontend)
- How to provide authorization, protection from eavesdropping and interception. Application attack model.
- Application compliance with European (GPDR) and Russian laws on personal data
- how notifications work on Android
- compliance with Russian legislation on the organizers of the dissemination of information
- Select a provider of cartographic information (google, yandex, bing), read the license
- components for photo processing
- in what resolution to store and in what to display
- how to arrange a backend for photos
- what are the performance requirements
- how unit and load testing is carried out