BraveDNS is an open source DNS Over HTTPS client, Firewall and ADblocker for Android
People started modding Linux- Powered Router's and access points long before the rise of Android.
Unsurprisingly such features are much requested in Android as well.
Features according to site :
DNS over HTTPS (circumvent censorship and prevent surveillance of DNS logs by ISPs and everyone else).
View DNS logs.
Ad-block through Adguard DNS.
Firewall by app categories.
Firewall individual apps.
Firewall when apps are in the background (not-in-active-use).
Firewall when device is locked.
While it is possible to configure Private DNS (or DNS-over-HTTPS) and subsequently block ads on an Android device since Android Pie, end-users still need to rely on third-party apps to set up a proper firewall.
If you are looking for an all-in-one app that can act as a firewall, adblocker, and even a DNS-over-HTTPS client, BraveDNS might interest you.
This free and open-source app describes itself as “an OpenSnitch-inspired firewall and network monitor + a pi-hole-inspired DNS over HTTPS client with blocklists”. The DoH client module, which is mostly based on another popular open-source project named Intra, uses AdGuard DNS as the default endpoint with built-in adblocking support.
The developer team also offers their own DNS resolver service as a paid option for those who need features like custom blocklists, allowlists, the ability to store DNS logs for later analysis, etc.
Requires Atleast Android Oreo.
This app is available in Playstore (early access) or Apk from Official website
You could also head over to Official website for 6 months premium and more info.