DNS over HTTPS is enabled by default. Note that there is a Settings page that lets you enable DoH but you won't able to save that page since this is not implemented yet.

This is fine because DoH is enabled in the underlying configs and it's just an UI issue.

To use Client ID identifiers, you can add aliases to the app.

A wildcard alias is set up to make it possible to identify somedevice by configuring it to make DoH requests to somedevice.adguard.domain.com.