You want LAN DHCP DNS servers to be blank so that your router IP is advertised to clients. Then dnsmasq will forward your requests to Unbound, and Unbound will not use your ISP DNS, but rather will send your queries out to the responsible (authoritative) DNS server for the domain you are querying. So if you request 5 different domains in one session, your requests will be sent to the 5 different name servers responsible for each of those domains. This is unlike default dnsmasq behavior which forwards every request to the same DNS server out on the internet (e.g. Quad9, Cloudflare, Google DNS, ISP, etc.) and they receive all your DNS query history. Using Unbound locally as the recursive resolver (i.e. the same function as Quad9, Cloudflare, Google DNS, etc.), you entrust your DNS history to no one entity except your own router.
Since the downside is that your ISP could still be snooping your DNS traffic from Unbound, I think the ideal scenario that I might try is to setup Unbound out in the cloud on a Linux server and have my router forward to it using DoT. That way no outbound DNS traffic is in the clear, except for the router's own lookups. Will have to think about that more.