dev-python/nose does not work with >=dev-python/setuptools-58 and >=python-3.9, also there are mentions upstream that it is deprecated for https://github.com/nose-devs/nose/issues/1099#issuecomment-562394879 nose2, and some projects (see same ticket below) already migrated to nose2.
nose2 is not a replacement, and given upstream's attitude I wish nobody would ever use nose2. pytest is a reasonable replacement.