Hi there
We have experience in developing educational apps.
In developing multi-user apps (in this app student, teacher, and admin) it requires some things to consider, including attention to the user-friendly design and appropriate UI/Ux.
The back-end can be built by Google Firebase as you wanted that provides several tools for you like tools for important analysis about the users or we can do it in Node.js that has better performance and is safer.
We have a team of experienced Designers & Developers who would be glad to help you shape your requirements into products.
Also, we support the app and fix bugs for 6 months so don't be worry about future bugs.
Hope to hear from you soon.
Thanks