Dear Sir!
It's really great to write my proposal over here.
Having read all that you posted, I am sure I can deliver the perfect results, as I am very familiar with React/Redux/Saga, Promise/Async and Python/Flask REST API.
With the exact understanding of the strategy, I would like to suggest you Firebase Cloud Notification service and Cloud function for Rest API , to reduce the server usage.
If you have any guidance about pricing or need to increase or decrease the scope of work, kindly just let me know.
I appreciate the opportunity to send you this proposal and I look forward to working with you!
Sincerely,
Jee Szes L.