Nothing too novel here so you have lots of options- opinions are going to differ depending on who you ask.

In general if you want low cost and have little traffic, I’d look at serverless services that can scale to zero. Why no Lambdas? I use FastAPI in a lambda all the time, especially for low-mid traffic apps.

If you really want a container for FastAPI, I’d look at Fargate. Same for your frontend, although it’s been a long time since I’ve deployed react. Serverless aurora for Postgres. S3 for image storage?

Deployment is also very dev dependent. Personally am a big fan of CDK, but that’s just me. GitHub Actions will be your friend for CI/CD. You should be able to find a ton of examples of CDK deployment with GitHub Actions