Is Rust a solid choice for developing highly scalable/high availability web based services?

I've written a mobile app in Flutter which, for convenience/speed to market, uses Firebase and various other Google services for the backend.

By the far the biggest cost for my app will be the bandwidth and storage costs I will be charged by Google for images (which you can upload/view from the app).

Therefore I eventually intend to implement my own custom backend(s). Then I can host it wherever I like and I think this will reduce my costs dramatically.

I'm (re)learning Rust for this purpose but, just today, I hear of a language called: Elixir which, as I understand it, is very efficient and fast for developing web backends that provide excellent concurrency.

Initially this would just be for images but eventually I would like to implement NoSql and authentication too.

Is it worth me learning another language for faster development or should I stick with Rust?

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Any advice appreciated.