Install it
Try https://chat.openai.com/?q=test
Install serach plugin
# run python server to serve chatgpt.html, for some reason it's not working if you open it like file:///
python -m http.server 8080
firefox localhost:8080/chatgpt.html
Follow open serach installation instructions https://support.mozilla.org/en-US/kb/add-or-remove-search-engine-firefox
Distribution
zip chatgpt.zip chatgptff.js manifest.json