Panel on Google AppEngine, standard environment instead of Flex


I have a Panel application running on Google Cloud Platform using the AppEngine flex environment as suggested by the server deployment guide: Server Deployment — Panel v0.14.3

runtime: python
env: flex
entrypoint: panel serve --address --port 8080 --allow-websocket-origin="*"

  python_version: 3

Is it possible to use standard Google AppEngine environments? These flex environments are much more expensive than their standard environment counterparts.
(Choose an App Engine environment  |  App Engine Documentation  |  Google Cloud)