Add the --show-all flag to the search subcommand to also see the unstable SDK and toolchain bundles. Unstable versions can include release candidates or other versions, as described in Versions and revisions in the nRF Connect SDK documentation.
The command extended with --show-all outputs the list of versions and their status for the default or selected installation directory:
> nrfutil sdk-manager search --show-all
Version SDK Toolchain
v2.9.0 Not available Available
v2.9.0-rc2 Not available Available
v2.9.0-rc1 Not available Available
v2.9.0-nRF54H20-rc1 Not available Available
v2.8.0 Installed Installed