I actually have a few production workloads running exclusively on ARM servers and have saved money doing so.

The applications themselves are in TypeScript, and Node as a runtime is cross arch without any extras. The hardest part is building docker images from my Github action.

I wouldn't be surprised to find out that AWS is secretly switching the hardware running of their serverless overrings to use their in-house chips. Things like lambda (assuming source is distributed), aurora serverless, Dynamo, Cognito, CloudFront, etc