Comparing the two repos, it seems pup is dead, but cascadia may not be.
These tools, including htmlq, seem to sell themselves as "jq for html", which is far from the truth. Jq is closer to the awk where you can do just about everything with json. Cascadia, htmlq, and pup seem closer to grep for html. They can essentially only select data from a html source.
[0] https://github.com/EricChiang/pup [1] https://github.com/suntong/cascadia