Monitoring all/selected apps's DNS queries with detailed information(application name domain name ip location etc.).
Force all/selected apps's DNS queries go through non-logging DoH/DNScrypt servers.
Add custom DoH/DNScrypt or UDP DNS servers.
Add block rules on apps/domains work as a simple android firewall.
Share/Copy DNS queries logs to anywhere you want.
For some types of phone please change the battery settings to make sure DoHGuard will not be killed by the System. 
If you search for a full-featured firewall please check another application Fiwalld out.