rpm-ostree install <pkg> is the equivalent of dnf install <pkg> with the same downsides of a traditional Linux OS (dependency hell which can break updates until the packages layered are remove.) We recommend Distrobox containers for having access to nearly every Linux package manager and repo, Homebrew for CLI/TUI packages over layering RPM packages (which is intended for system-level stuff only).
Click on each package format in this doc for more information on installing software on Bazzite:
https://universal-blue.discourse.group/docs?topic=35