Instead of making changes inside a running container, the best practice is to define your desired state in a Containerfile (or Dockerfile). This is a simple text file with instructions.
A Containerfile for your example would look like this:
# Start from the base Fedora image
FROM fedora:latest
# Install the nano editor during the build process
RUN dnf -y install nano && dnf clean all
# The default command to run when the container starts
CMD ["/bin/bash"]
You would then build this into your own custom, reusable image:
podman build -t my-custom-fedora .