Multi Tenant Azure AD App with Azure Function

I am working on creating an Azure Function that is secured by an Azure AD App. I have the Azure Function part working and it is secured by Azure AD but now I would like to allow users in other tenants to be able to call this Azure Function and access the resources in their tenant. When I share the link to the Azure Function with a user the auth part works fine but then I get the following message.

 

Selected user account does not exist in tenant '{TenantName}' and cannot access the application '{ApplicationID}' in that tenant. The account needs to be added as an external user in the tenant first. Please use a different account.

 

Is there any way for me enable this scenario short of adding the user as a guest in the tenant?