dual wan router to Orbi SRR60 system

Have an existing Orbi SRR60 router steup with multiple Orbi mesh satelites (interconnected by LAN and 5G backhauling).

Would like to put a dual wan router (examples: Netgear Prosafe 336, Linksys LRT224) between ISPs and Orbi SRR60.  This way, the dual WAN will provide uninnterupted ISP service to the Orbi SSR60 setup.  How is this accomplished?  Thanks!