I guess they've been working on DoH3 in the background recently...

A month or so ago I found the doh3.dns.nextdns.io to specify using doh3 where possible. I've been able to get this to work on android by using the adguard app, turning off all adguard's features apart from DNS, going into the low level settings and turning on HTTP/3, finally adding the above as the dns url as follows: h3://doh3.dns.nextdns.io/xxxxx

It was a bit hit and miss, sometimes working and sometimes falling back to DoH. But lately, it has been rock solid on DoH3 and even works with the regular url dns.nextdns.io/xxxxx.

Yesterday I noticed that chromium based web browsers on windows also work with DoH3 (though they do give an error message when the url is entered, a visit to test.nextdns.io shows it is working with DoH3.