Alex from the OpenFaaS open source project here. We recently had some help from the Istio team to update the compatibility and support for OpenFaaS + Istio. I went on to then write it up in as much detail as I could and show some of my own thoughts.
Hope you enjoy, and feel free to ask me questions on Twitter -
https://twitter.com/alexellisuk or CNCF/OpenFaaS Slack