Or (dare I say) look into EKS. Kubernetes can spin up containers faster than ECS in my experience (as of ~1 year ago). Seems like the ECS control plane just has more latency (even with EC2 instead of Fargate)
If pods have added privileges or there is a really low risk tolerance, maybe that's not enough isolation.
Sounds like you can change the container runtime with EKS (not sure if that impacts AWS support) so you could use gVisor or runvm
https://www.verygoodsecurity.com/blog/posts/secure-compute-p...