Hi,
Port Channel on MX WAN Interfaces? I believe shall not be possible.
Port Aggregation feature is available on switches. WAN interfaces can offer us Load balancing and Load sharing features.
Check the following Url for more information
https://documentation.meraki.com/zGeneral_Administration/Tools_and_Troubleshooting/Link_Aggregation_....)
Regards,
Ajit
AjitsNW@gmail.com
www.ajit.network