What about burstable instances on AWS, and whatever is the equivalent in other clouds? Hard to imagine those having a dedicated core, would probably defeat the purpose.
AWS Fargate, container as a service, allows specifying 0.25 or 0.5 CPU, and I would be surprised if those weren't shared.
Same probably? also applies to AWS Lambda.
It's more likely useful as part of a group of exploits to hit an individual, targeted system.
LLM's might change that. getting a firehouse of data and asking it to classify controls against NIST 53- rev5 produces interesting results.