You have a graph that shows a multi provider setup for a domain. Where would routing to either machine happen? As in which ip would you use on the dns side?
For the public cluster with multiple ingress (caddy) nodes you'd need a load balancer in front of them to properly handle routing and outage of any of them. You'd use the IP of the load balancer on the DNS side.
Note that a DNS A record with multiple IPs doesn't provide failover, only round robin. But you can use the Cloudflare DNS proxy feature as a poor man's LB. Just add 2+ proxied A records (orange cloud) pointing to different machines. If one goes down with a 52x error, Cloudflare automatically fails over to the healthy one.
I looked into this yesterday for making Caddy HA on my Proxmox cluster and stumbled upon keepalivd. It will provide you with a virtual IP and failover but not load balancing so you'd need to still point that at something like HAProxy for that.
Could be something interesting to integrate though.
As I mentioned in the sibling comment, please note that in this case you only get round-robin, not failover. If one of the addresses is down, the DNS record will continue returning it and users will hit a dead end.
A proper load balancer or Cloudflare DNS proxy would handle this.
