Still not following. Are you setting up containers with portainer or something? My whole docker setup is in one docker-compose.yml. I use docker compose, not docker-compose. Maybe that's the issue?
Edit: that link is about running docker in Windows 10.
I think I'm going to have to spin up a VM to understand why you're doing things the way they are, instead of using a .env file with the docker-compose.yml, or docker secrets. The built-in way to run containers is very straightforward, and it seems at first glance that you're making it a bit more complicated than it needs to be. There's no need to mess with systemctl at all, for example.