Resolution of the router's own hostname
DNS using unbound is working more or less like I want it to. It is able to respond to queries for hostnames of machines on the LAN with the LAN's configured DNS suffix.
There's a quirk - pfSense refuses queries from LAN clients to resolve the router's own hostname. I've worked around this by adding a host override in the resolver configuration page. Why should this be necessary? Shouldn't pfSense already be able to respond to queries about its own hostname?
No. Setting the hostname does not put anything in DNS. You need the host override if you want to resolve the name.
OK. Well that's good to know. I would propose that this is "surprising" behaviour, and at the least, an option should be introduced to the UI such as "Add entry in DNS to resolve router hostname". This is a common-enough problem, I'm sure, that it would be a useful feature.