Thanks for your reply Meyay!
This was my idea too (i.e. implement in my Dockerfile each required steps like adding Mermaid, Pandoc and Reveal.md) so my Dockerfile will be self-sufficient. This was neverthless not my “way-to-go” choice because I need to isolate from these three images all the stuff I need to put in my own Dockerfile script and, also, maintain it.
It would have been really comfortable to just do a docker run to call up these images; without having to “integrate” them into mine. The size of my image would also have remained very small (just a few Bash scripts).
I fully understand meanwhile that it’s not possible; too specific for my own use case.