Hi @Shamatix,
AFAK, current external user can only access by click on the share the email link. Perhaps you can submit an idea about this requirement.
Share a dashboard with people outside your organization
When you share with people outside your organization, they get an email with a link to the shared dashboard, and they have to sign in to Power BI to see the dashboard. If they don't have a Power BI Pro license, they can sign up for one after clicking the link.
After they sign in, they see the shared dashboard in its own browser window without the left navigation pane, not in their usual Power BI portal. They have to bookmark the link to access this dashboard in the future.
They can't edit any content in this dashboard or report. They can interact with the charts in the report (cross-highlight) and change any filters/slicers available on the reports connected to the dashboard, but can't save their changes.
Only your direct recipients can see the shared dashboard. For example, if you sent the email to Vicki@contoso.com, only Vicki can see the dashboard. No-one else can see that dashboard, even if they have the link, and Vicki has to use the same email address to access that dashboard. If she signs up with any other email address, she won't have access to the dashboard either.
People outside your organization can't see any data at all if role- or row-level security is implemented on on-premises Analysis Services tabular models.
If you send a link from a Power BI mobile app to people outside your organization, when they click the link the dashboard opens in a browser, not in the Power BI mobile app.
Reference link:
Share dashboards with coworkers and others
Regards,
Xiaoxin Sheng
Community Support Team _ Xiaoxin
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