[vanrysss]

It depends, if it's just you and you want to get to market quickly building your web app and backend in Rails backed by postgres and redis is still a solid choice. Put your code in docker and have AWS' ECS Fargate manage it, do the same for your DB(Aurora) and cache(Elasticache). I can't speak for mobile devs, but it sounds like a lot of the hype around react native and whatnot has died down.

A bigger org I'd probably just change the backend code to Go and start taking advantages of other AWS products to manage ETL/monitoring/logging/etc. The change to Go is mostly just to prevent your more 'clever' engineers from producing code that no one but them can understand. Languages like Clojure and Scala while cool can start causing real problems in an org where the experience level isn't uniform.

A note on tech that bears repeating, if it isn't going to be your differentiator then choose boring building blocks.