This is a simple Hot Network Questions Custom RSS feed filter
it is based on the work done in SE Hot Network Scraper
The /hnq/:site endpoint accepts a site or list of sites to include / exclude from the Hot Network Questions List for Mobile
for example /hnq/askubuntu will filter the current HNQ list to only posts that come from askubuntu.com.
to have both English Language Learners (ell) and English Langusge Usage (english) do/hnq/+ell+english
to have all sites that are not in the stackexchange domain do/hnq/-stackexchange
The logic will first apply what you want to include and then runs the exclude logic
add the url in the feeds tab of your chatroom.