Hi Mark,
GSAP can be used inside Widget elements in Bannerflow. Widgets are custom elements that are created using your own HTML, CSS and JS/TS code. To include the GSAP library in a widget, make sure to use a trusted and whitelisted third-party domain like:
https://cdnjs.com/libraries/gsap
Embed the GSAP script tag in the HTML section of the widget, and apply your animations in the JavaScript section.
Feel free to reach out to Bannerflow Support and they will help you prepare an example.
Kind regards
Daniel