It looks like the project became inactive for a bit and there are alternatives such as htmlq, etc. https://github.com/ericchiang/pup/issues/150
$ curl -s https://news.ycombinator.com/ | fq -r -d html 'grep_by(."@class"=="titleline").a."#text"'
Inkbase: Programmable Ink
New details on commercial spyware vendor Variston
How We Built Fly Postgres
...
$ curl -s https://news.ycombinator.com/ | fq -r -d html '{hosts: {host: [grep_by(."@class"=="titleline").a."@href" | fromurl.host]}} | toxml({indent:2})'
<hosts>
<host>www.inkandswitch.com</host>
<host>blog.google</host>
<host>fly.io</host>
...
</hosts>
See https://github.com/wader/fq/blob/master/doc/formats.md#xml and https://github.com/wader/fq/blob/master/doc/formats.md#html for examples and documentations.