avidgrapher
The access can be implemented through adding a textbox in settings.
The OS images are immutable beyond updates and are verified from a root of trust. Modifying the hosts file is not ever an appropriate way of filtering DNS requests rather than doing it in a way that provides proper errors regardless. Adding a third way to do something that's increasingly less impactful instead of implementing truly fundamentaly privacy and security improvements is highly unlikely.
Whether this is a good aside is a separate issue. It only impacts connections made after a query to retrieve an IP via the system DNS resolver. The lists you'd be using are best efforts attempts to enumerate domains belonging to certain categories without breaking actual functionality. A telemetry blocking list can't block a domain used for both telemetry and actual functionality or it would break apps and sites. Many domains are dual purpose and therefore won't be blocked even if they're widely used and known about. Anything new or not widely known about won't be blocked. It has all the same issues as the antivirus approach of enumerating badness. It's already possible to do this filtering in 2 different ways on GrapheneOS.
The problem with VPN is it's an overkill for just blocking few sites and battery-consuming too.
You can filter DNS results by either using the Private DNS feature or a VPN service.
The VPN service feature can be used by apps which only provide their own DNS resolver rather than VPN. There are also actual VPN implementations which support local or remote filtering of DNS queries.
Using a VPN service which provides only a custom local DNS resolver won't use significant power since it's not routing traffic through it. Only requests to the system DNS resolver are going through it.
The problem with DNS is it adds to your fingerprint. It's not recommended by GrapheneOS FAQ.
Filtering of DNS results is detectable by services including web sites, not just the DNS resolver server that you're using. If you're concerned about fingerprinting by services, filtering DNS requests this way isn't on the table. It doesn't provide a fundamental privacy improvement regardless.
This has been requested before
Please don't create duplicate threads, especially without reading all the responses in previous threads.