Firefox and Chrome at least have both implemented this.
Apple supports it at system level since Big Sur or Monterey I believe, but with limited efficacy, since use of network extensions (Lulu, Little Snitch etc.) silently bypasses a provisioning profile DNS over HTTPS setup. It works fine on mobile though.
The suggestion is for Orion to support selection of a DNS-over-HTTPS server, and allow entry of a custom URL. This is good for privacy and security, as it helps users to avoid relying on their ISP DNS. You can also do host-level ad/tracker/malicious content filtering.
A couple of "defaults" are available (if you enable the feature, which is currently default-off, I believe, Cloudflare is the selected default).
And you can enter your own server URL if you like: