Yah, as I understand it (not a sysadmin, just hobby stuff), if you want to run something in docker, you'd have to setup the system first and then docker on top of that. I'm not sure you need the docker layer though - it's unnecessary overhead probably. Each VM/container could just have the necessary OS with the packages needed for that particular use case installed directly.

Guessing someone who tried to use a system like this would probably have their own custom containers / linux distributions, or at least have custom install scripts that would function much like the docker compose file does in getting everything installed on that container for different use cases.