> +(defcustom tramp-docker-program "docker"
> +  "Name of the Docker client program."
> +  :type '(choice (const "docker")
> +                 (const "podman")
> +                 (string))
> +  :group 'tramp-docker)

It's not unusual to have both podman and docker containers on the same
host. But the way tramp-docker.el is arranged currently, it's difficult
to have simultaneous tramp connections to both of them. I think it would
make sense to have two tramp methods: '/docker:' and '/podman:', and by
extension, two defcustoms: tramp-docker-program and
tramp-podman-program.