I'm guessing CDK Pipelines are out of the question because they deploy CloudFormation? They're the main benefit of AWS CDK for me, making CI/CD seamless and abstract, is there are alternative?

Apologies for the delay here. Yes as it stands CDK pipelines are not supported. There are a bunch of complications here stemming from the self-mutating nature and the strong assumptions on how the cdk stacks are synthesized. I imagine we could support a somewhat restricted form of this in the future. FWIW we have a pretty extensive library on CI/CD integration for pulumi here including for code services: https://www.pulumi.com/docs/guides/continuous-delivery/aws-code-services/ but this is going to look closer to running a Pulumi stack than a CDK stack. Happy to ponder ideas here if you open an issue in https://github.com/pulumi/pulumi-cdk/issues