You don't need to have two different vendors to interoperate and get into comparability issues or inter-operability issues.
Fortinet FortiExtender streamlines operations through centralized management and integrates with solutions like 5G LTE and cellular networks. It serves as an active secondary link or backup but has challenges in troubleshooting compared to Cisco. Users suggest a smaller footprint for mobile clients and improvement in SIM handling. Pricing, especially for 5G models, is a concern. Embedded SD-WAN features could enhance WAN management, making it function seamlessly like a standard internet connection.