I don't know GCP well but it looks like the GCP CloudFunctions and AWS Lambdas are similarly related. They'll have a limited run time since they're meant for small tasks. Thus they probably won't be able to run NestJS, however, from the way the GCP API's are written, you could maybe integrate a Gateway API endpoint to a GCP CloudFunction.
Sorry I'm not much help because I don't really use GCP.