Personally I use Unbound as a DNS cache. When devices on my LAN ask for nameserver addresses, my router is configured to point to the IP of the Unbound server (which in my case happens to also be the router, but you could run Unbound on any machine on your network as long as it's got a static IP).
Don't forget that if you have DoH, it is bypassing your local resolver. Then, you're giving your juicy DNS data to the DoH provider rather than your ISP. One of the best videos I've seen that talks about these issues is form the Southern California Linux Expo this year: https://www.youtube.com/watch?v=artLJOwToVY
I suppose the obvious question is, does IPv6 work for you under normal circumstances? Many ISPs don't support it even in 2020. I'm quite sure CenturyLink doesn't and I've never gotten it to work under Comcast either.
Comcast should work well, they were one of the first major ISPs to provide IPv6 for consumers. Using DHCP-PD, they'll assign a /60 to you. So you can have 16 LANs running at your house -- all with addresses that aren't NATed. I haven't worked with CenturyLink's IPv6 offerings.