You can point the official docker-compose at podman now!
I do that!
It's 99.999% compatible as the podman people basicaly reimplemented all the docker daemon APIs.
It sometimes lags a bit behind, because sometime docker implements new stuff... But for usage with docker-compose it has worked flawlessly for me.
EDIT: you can also export the podman unix socket via socat, i also tried it to run a rootless docker runtime in kubernetes (podman daemon running as a pod, to run docker builds in kubernetes) as an experiment. It works but i'd love to see a better integration with Gitlab runner project.
Gitlab is supposedly getting podman support any time soon, in 15.1 IIRC ?