Ha, that's awesome indeed!
(EDIT: Please don't read this without reading the reply, as there is an important correction. I am not 100% sure that the docker container pulled through ghcr.io is guaranteed to be built from the source code that is publicly available)
Since the github page doesn't explain how the installation works for those who aren't familiar with docker, I can add a quick explanation:
If you are using Linux and you have already installed docker, all you need to do is to run the following command in the terminal (replacing lemmydomain.com with the instance you use):
docker run -it -e LEMMY_DOMAIN='lemmydomain.com' -p "8080:8080" ghcr.io/rystaf/mlmym:latest
This command will create the docker container directly by pulling the code from github, and it will host the application on your computer, accessible at port 8080. So, you would then open your browser and type "localhost:8080", and it this will take you to your instance but with an interface that looks like the old reddit.