how can I download podcasts to ipod nano now without itunes.

Hello,

You must use iTunes on an older Macintosh or Windows PC or by using the Finder on a Macintosh running macOS 10.15 Catalina.

Sync your iPhone, iPad, or iPod using your computer - Apple Support

You now have a dedicated app called Podcasts. You manage them in this app.

To sync your device, you now use Finder. Open any Finder window and look for your iPod in the sidebar, under the Locations heading.