I have added Port Forwarding rules to redirect ports 53 & 853 to my OpenWrt router. That is working well for 'Desktop Chrome' with 'Secure DNS' enabled in the application.
Android Chrome isn't playing ball and is circumventing the DNS rules.
I've tried redirecting 8.8.8.8 and 8.8.4.4 ports 53 & 853 to OpenWRT, but it's still failing.
Security is relative and depends on what we consider to be a threat or not.
Moreover, security that silently falls back to an insecure protocol is questionable.