Backup internet questions

Hello everyone. I'm thinking about upgrading to the Pro base station for my home because I like the idea of backup internet. What I need to know is how it works. I have a robust configuration here now. Modem->Firewall->Switch->Access Points. How is the backup internet provided to my network? If it's just broadcasting WiFi on its own, that's not very useful to me at all. I need it to be able to push data into my network, so ideally it has an ethernet connection that I can route to my firewall and disable any internal WiFi. My firewall can handle the fail-over on its own, but if not, it would have the same effect for the Ring to handle fail-over, I can make the changes on my firewall to accommodate that.