Maybe we are referring to different things when we say 'process'... I am not aware (happy to be educated) of Firezone having SDKs to embed the zero trust overlay running directly in an application, i.e., in the app process and memory.
Do they support this?
I hear you on having 'out of process', that's why OpenZiti also has tunnellers for deploying on host as well as virtual appliances to run in the DMZ/VNET/VPC etc. I was only aware of Firezone supporting those 2 deployment models.