Okay lots of good info here but just to make sure it was clear that you are kinda solving two different but related problems. Connectivity with WireGuard or other VPN and split-horizon or multi-horizon DNS (Wikipedia) which also called a view sometimes (like BIND) and can also be done with two different DNS servers. You can sorta do it with AdGuard but it is tedious to maintain. If you are using a wildcard rewrite it works alright but that isn’t necessarily the same as a CNAME or subzone delegation.
The next pice I’m not sure I saw mentioned is that WireGuard is not like other VPNs in that if two nodes are on the same network they will generally communicate directly peer to peer even over WireGuard addresses so you don’t really need to worry about traffic hairpin like you described unless you configure it to do so (which is more like traditional VPN would act). Tailscale is similar in concept but it uses different terms and technologies.
Anyway not sure if that helped or made it more confusing but there are may ways to solve it so good luck! FWIW, my home network is currently set up with a public zone on a commercial provider. It has a wildcard CNAME to something like proxy.domain and that is an A record containing the WireGuard addresses. Then my local DNS overrides the one A record for the proxy internally which I only get when WG is off. I would rate this solution adequately functional but medium level of janky, 8/10 would use again :D
Okay lots of good info here but just to make sure it was clear that you are kinda solving two different but related problems. Connectivity with WireGuard or other VPN and split-horizon or multi-horizon DNS (Wikipedia) which also called a view sometimes (like BIND) and can also be done with two different DNS servers. You can sorta do it with AdGuard but it is tedious to maintain. If you are using a wildcard rewrite it works alright but that isn’t necessarily the same as a CNAME or subzone delegation.
The next pice I’m not sure I saw mentioned is that WireGuard is not like other VPNs in that if two nodes are on the same network they will generally communicate directly peer to peer even over WireGuard addresses so you don’t really need to worry about traffic hairpin like you described unless you configure it to do so (which is more like traditional VPN would act). Tailscale is similar in concept but it uses different terms and technologies.
Anyway not sure if that helped or made it more confusing but there are may ways to solve it so good luck! FWIW, my home network is currently set up with a public zone on a commercial provider. It has a wildcard CNAME to something like proxy.domain and that is an A record containing the WireGuard addresses. Then my local DNS overrides the one A record for the proxy internally which I only get when WG is off. I would rate this solution adequately functional but medium level of janky, 8/10 would use again :D