Hello,
there's an alternative and drop-in replacement to docker called podman that allows to run container without the docker daemon and in user space (most users don't care about this, but who is concerned with multi-user system security might care).
Podman also facilitates the transition to Kubernetes because it has the concept of "pod", used by kubernetes but not by docker, which is a set of containers running in the same isolated namespace: they can communicate freely with each other, but are isolated from the rest of the system. (EDIT: this is a sort of alternative to docker compose.)
Now, for the few out there interested in this, I made some instructions to have flarum up and running with nginx, mariadb and php 7.4-fpm. You're welcome to run, test and give feedback.
Here's the flarum-podman repo, that I tested on Fedora 29 and 31.
I'm not familiar with the k8s yaml format for pods, so the repo is just a bunch of instructions in a README file, but in theory it should be possible to run the entire pod easily with just a command, like podman kube play somefile.yaml.
Maybe I'll give it a try in the future.
Hope you like it!
Ale
