For anyone interested, recently I had to research opensource visual page builder/websites options and these were top of the list:
https://github.com/prevwong/craft.js (React)
https://github.com/paperbits/paperbits-core (Full website, uses Firebase)
https://github.com/react-ui-builder/react-ui-builder-editor (React)
https://github.com/premieroctet/openchakra (Editor for Chakra UI)
https://github.com/BuilderIO/builder (Not sure if this really is open source)