I think it would be a good idea to allow admins to either set a global default dashboard for all users or to set a default by user group. Users then should have the ability to change their default dashboard. It’s a little confusing for some new users when they log in and are shown a list of dashboards. I would prefer it if we could direct them to one by default and then later educate them on how to navigate to others.
Why not give them a direct link to the actual dashboard or just share the public dashboard link with them?