How to give access to a shared mailbox for a Guest/External user?

Question

Hello Experts,
I am having trouble providing access to a shared mailbox for an external user.

Is this even possible? I've created the Guest user in Azure AD, Assigned some licenses to the user but am still unable to add the user to the desired shared mailbox.

Of course I have no issues adding "someone@myorganization.com" to the mailbox, but the external user - "someone@externalorganization.com" simply can not be added to the shared mailbox.

Am I missing something? Can I assign a license to the mailbox itself, reset password and provide it to the external user, so he can log into the shared mailbox? If it's possible could someone provide guide for it?

I've read that you can add the domain of the external organization to the tenant, but that does not seem like a good solution.
Adding the external user - "someone@externalorganization.com" to Contacts and Creating a Distribution group also isn't a good alternative.

Answer 1

Not possible.
https://learn.microsoft.com/en-us/microsoft-365/admin/email/about-shared-mailboxes?view=o365-worldwide

Answer 2

@Andy David - MVP Thanks for the quick response. As an alternative I have created a Microsoft 365 Group and added the external user there. Does the Microsoft 365 Group have shared mailbox capabilities or it's just like a distribution list, combined with a calendar, file sharing etc. ?