Right, there’s an issue in the default priorities of the various rules in Knot Resolver, so that you don’t get reverse local hints by default. For IPv4 I would do it by adding this single line:
policy.add(policy.suffix(policy.PASS, {todname('1.168.192.in-addr.arpa.')}))
(people using different address range for LAN will need to tweak it) And here’s how to add this line: https://doc.turris.cz/doc/en/public/dns_knot_misc#adding_custom_configuration
EDIT: link to upstream thread: https://gitlab.labs.nic.cz/knot/knot-resolver/issues/205#note_94567