Basically, any Docker image can be used as a base and also the image contents can be freely selected. This is because the ExaMesh platform launches the resulting containers as usual native Docker processes, without any additional proprietary requirements or other magic. This aspect is part of the basic ExaMesh design philosophy:
The ExaMesh platform only takes care of launching containers and exposing associated endpoints (TCP ports). Whether these endpoints can be addressed at runtime of the container depends solely on the content of the image and the associated Docker Compose configuration that is created during instance startup.