flytectl demo/sandbox is not meant for production, it's essentially a vm running on your local computer to get you familiarized with how flyte works quickly.
If you want production level, you have 2 options:
1.
deploy in kubernetes cluster hosted through a cloud provider (e.g. google, amazon, azure)
2.
deploy to an on-premise kubernetes cluster (harder and larger upfront investment if you don't have the hardware)
You choose option 1 to get started more quickly, but option 2 is better if you're prioritizing security (i.e. you don't your data/code stored in cloud provider)