How can I lookup the IP address of a Bonjour host?
Use dns-sd

It's the Multicast DNS (mDNS) &amp; DNS Service Discovery (DNS-SD) tool for BSD. 

$ dns-sd -Gv4v6 &lt;hostname&gt;.local


For my example, I write:

$ dns-sd -Gv4v6 raspberrypi.local


And get the IP (redacted) in the address column:

DATE: ---Wed 19 Jun 2019---
14:23:40.213  ...STARTING...
Timestamp     A/R    Flags if Hostname               Address         TTL
14:23:40.531  Add        2  5 raspberrypi.local.     &lt;redacted MAC&gt;  120
14:23:40.548  Add        2  5 raspberrypi.local.     10.1.2.3        120
14:23:40.838  Add        3  5 raspberrypi.local.     &lt;redacted MAC&gt;  120
14:23:40.838  Add        2  5 raspberrypi.local.     10.1.2.4        120


Hostnames and IP addresses have been changed to protect the innocent. I found this answer by looking for other questions about finding Bonjour machines.