Is there a list for this?
I have Verizon for my current WAN connection, I am hoping to sign up for a 4G/5G LTE service in my area and use that for failover in the event of the internet lines going down.
Any advise on hardware for this would be appreciated.
I use a NETGEAR LB2120 (https://www.netgear.com/au/home/mobile-wifi/lte-modems/lb2120/) and a "spare" ethernet port on the firewall.
You could setup your WAN with an additional tagged VLAN (perhaps labelled WAN-4G) and trunk the two into a perimeter switch and then break out the VLANs to bastion hosts and ISP routers as necessary.
It does have an in-built router but I use mine in bridge mode.
I like how it's all ethernet. It works well in a gateway group and OPNsense works well at directing traffic to particular gateways as needed.
It's showing it's age now though, I had to tape the last nano SIM into a micro cut-out. It might also have gigabit ports but it's maximum theoretical speed is 150Mbps.
NETGEAR have other options now too, such as the MR2100 (https://www.netgear.com/au/home/mobile-wifi/hotspots/mr2100/) with up to 2Gbps, but perhaps somewhat overkill with dual-band Wi-Fi and the works such as a colour touch screen, etc.
I'm sure there are a number of other players out there as well.