Wireguard Site to Site with a Mudi V2 (GL-E750V2) Portable 4G LTE Router

[tuaris]

I recently got my hands on a Mudi V2 (GL-E750V2) Portable 4G LTE Router.  The device has Wiregaurd capabilities (as well as OpenVPN).  Use Guide: https://docs.gl-inet.com/router/en/4/user_guide/gl-e750/

I'm still new to WG, but I have a good grasp on how it gets configured.  I would like to setup a "site-site" connection between this mobile router and an OPNSense device.  I am having trouble 'translating' the configuration concepts to the mobile router.  The OPNsense device has a static public WAN address.  The mobile router's IP will always be dynamic and may not always be public.  It could be sitting behind a NAT, it could be directly on the public Internet.  It depends where I am.

Has anyone had any experience with this device?  If so, could you share an example configuration?