Hello Sir/Ma'am,
I've extensive knowledge on enterprise application development and delivery. I can even help you with designing the architectural/application flow as well. As you've mentioned Spring boot and databases(SQL/NoSQL), I've thorough knowledge in this but don't have any experience in android.
You can get the application built in using following languages or technologies:
Java, Spring boot, JPA, Hibernate, NodeJs, Angular, MongoDB, Oracle SQL.
Once assigned, we can discuss the timelines and milestones of the project. I can also help in deploying the application and post delivery support too if needed.
Timings of working for the project and rates are adjustable. I'll be looking for good relationship throughout and after the project too.