Enable cross-tenant access in the Azure Active Directory tenant settings and configure the Microsoft Entra Internet Access policy to allow traffic from all tenants without any restrictions.

Create and manage a separate Microsoft Entra Internet Access policy for each tenant, configuring each policy to allow traffic only from its specific tenant, which increases administrative overhead.

Implement a centralized identity and access management solution to manage user identities and permissions across all tenants, ensuring secure and compliant access to Microsoft 365 services.

Deploy a VPN solution to establish secure connections between the tenants, which may introduce latency and complexity without addressing identity management needs.